Exposure apparatus and exposure method, and flat panel display manufacturing method

ABSTRACT

In an exposure apparatus, on a substrate holder ( 34 ), a plurality of grating areas (RG) is arranged mutually apart in the X-axis direction, and a plurality of heads ( 66   a  to  66   d ) that irradiates a measurement beam with respect to the grating area and can move in the Y-axis direction is arranged outside of the substrate holder. A control system controls movement of the substrate holder in at least directions of three degrees of freedom within an XY plane, based on measurement information of at least three heads of the plurality of heads facing the grating area and measurement information of a measurement device that measures position information of the plurality of heads. The measurement beam of each of the plurality of heads, during the movement of substrate holder in the X-axis direction, moves off of one of the plurality of grating areas and switches to another adjacent grating area.

This is a Divisional of U.S. patent application Ser. No. 15/763,432filed Mar. 26, 2018, which is the U.S. National Stage of InternationalApplication No. PCT/JP2016/078778 filed Sep. 29, 2016, which claimspriority from Japanese Application No. 2015-195268 filed in Japan onSep. 30, 2015. The disclosure of each of the above-identifiedapplications is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present invention relates to exposure apparatuses and exposuremethods, and flat panel display manufacturing methods, and moreparticularly, to an exposure apparatus and an exposure method used in alithography process for producing micro-devices such as a liquid crystaldisplay device, and a flat panel display manufacturing method using theexposure apparatus and the exposure method.

BACKGROUND ART

Conventionally, in a lithography process for producing electronicdevices (micro-devices) such as a liquid crystal display device or asemiconductor device (such as an integrated circuit), exposureapparatuses are used such as an exposure apparatus of a step-and-scanmethod (a so-called scanning stepper (also called a scanner)) thattransfers a pattern formed on a mask irradiated with an energy beam,while a mask (photomask) or a reticle (hereinafter collectively called a“mask”) and a glass plate or a wafer (hereinafter collectively called a“substrate”) are moved synchronously along a predetermined scanningdirection (scan direction).

As this type of exposure apparatus, an exposure apparatus equipped withan optical interferometer system is known that obtains positioninformation within a horizontal plane of a substrate subject to exposureusing a bar mirror (long mirror) that a substrate stage device has (forexample, refer to PTL 1).

Here, in the case of obtaining position information of the substrateusing the optical interferometer system, influence of the so-called airfluctuation cannot be ignored. While the influence of air fluctuationmentioned above can be reduced using an encoder system, due to theincreasing size of substrates in recent years, it is becoming difficultto prepare a scale that can cover the entire moving range of thesubstrate.

CITATION LIST Patent Literature

-   [PTL 1] U.S. Patent Application Publication No. 2010/0018950

SUMMARY OF THE INVENTION Means for Solving the Problem

According to a first aspect of the present invention, there is providedan exposure apparatus that irradiates an object with an illuminationlight via an optical system, comprising: a movable body arranged belowthe optical system that holds the object; a drive system that can movethe movable body in a first direction and a second direction orthogonalto each other within a predetermined plane orthogonal to an optical axisof the optical system; a measurement system in which one of a gratingmember with a plurality of grating areas arranged mutually apart in thefirst direction and a plurality of heads each irradiating the gratingmember with a measurement beam that can move in the second direction isprovided at the movable body, and the other of the grating member andthe plurality of heads is provided facing the movable body, themeasurement system having a measurement device that measures positioninformation of the plurality of heads in the second direction, and themeasurement system measuring position information of the movable body inat least directions of three degrees of freedom within the predeterminedplane, based on measurement information of at least three heads of theplurality of heads irradiating at least one of the plurality of gratingareas with the measurement beams and measurement information of themeasurement device; and a control system that controls the drive systembased on position information measured by the measurement system,wherein the measurement beam of each of the plurality of heads moves offof one of the plurality of grating areas and moves to irradiate anothergrating area adjacent to the one grating area, while the movable body ismoving in the first direction.

According to a second aspect of the present invention, there is provideda flat panel display manufacturing method, comprising: exposing asubstrate using the exposure apparatus according to the first aspect;and developing the substrate that has been exposed.

According to a third aspect of the present invention, there is providedan exposure method irradiating an object with an illumination light viaan optical system, comprising: measuring position information of amovable body in at least directions of three degrees of freedom within apredetermined plane orthogonal to an optical axis of the optical systemby a measurement system in which one of a grating member with aplurality of grating areas arranged apart from the plurality of firstgrating areas in a second direction orthogonal to the first directionwithin the predetermined plane and apart from one another in the firstdirection, and a plurality of heads each irradiating the grating memberwith a measurement beam that can move in the second direction orthogonalto the first direction within the predetermined plane is provided at themovable body, and the other of the grating member and the plurality ofheads is provided facing the movable body, and by the measurement systemhaving a measurement device that measures position information of theplurality of heads in the second direction, position information of themovable body is measured based on measurement information of at leastthree heads of the plurality of heads irradiating at least one of theplurality of grating areas with the measurement beams and measurementinformation of the measurement device; and moving the movable body basedon position information measured by the measurement system; wherein witheach of the plurality of heads, the measurement beam moves off one ofthe plurality of grating areas, and moves to irradiate another gratingarea adjacent to the one grating area while the movable body is movingin the first direction.

According to a fourth aspect of the present invention, there is provideda flat panel display manufacturing method, comprising: exposing asubstrate using the exposure method according to the third aspect; anddeveloping the substrate that has been exposed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view schematically showing a structure of a liquid crystalexposure apparatus according to a first embodiment.

FIG. 2 is a view showing an example of a substrate stage device that theliquid crystal exposure apparatus of FIG. 1 is equipped with.

FIG. 3A is a view schematically showing a structure of a mask encodersystem, and FIG. 3B is an enlarged view of a part of the mask encodersystem (part A in FIG. 3A).

FIG. 4A is a view schematically showing a structure of a substrateencoder system, and FIGS. 4B and 4C are enlarged views of a part of thesubstrate encoder system (B in FIG. 4A).

FIG. 5 is a side view of a head unit that the substrate encoder systemhas.

FIG. 6 is a cross sectional view of line C-C in FIG. 5.

FIG. 7 is a schematic view of the substrate encoder system.

FIG. 8 is a block diagram showing an input/output relation of a maincontroller that mainly structures the control system of the liquidcrystal exposure apparatus.

FIG. 9A is a view (No. 1) showing an operation of the mask encodersystem at the time of exposure operation, and FIG. 9B is a view (No. 1)showing an operation of the substrate encoder system at the time ofexposure operation.

FIG. 10A is a view (No. 2) showing an operation of the mask encodersystem at the time of exposure operation, and FIG. 10B is a view (No. 2)showing an operation of the substrate encoder system at the time ofexposure operation.

FIG. 11A is a view (No. 3) showing an operation of the mask encodersystem at the time of exposure operation, and FIG. 11B is a view (No. 3)showing an operation of the substrate encoder system at the time ofexposure operation.

FIG. 12A is a view (No. 4) showing an operation of the mask encodersystem at the time of exposure operation, and FIG. 12B is a view (No. 4)showing an operation of the substrate encoder system at the time ofexposure operation.

FIG. 13A is a view (No. 5) showing an operation of the mask encodersystem at the time of exposure operation, and FIG. 13B is a view (No. 5)showing an operation of the substrate encoder system at the time ofexposure operation.

FIG. 14A is a view (No. 6) showing an operation of the mask encodersystem at the time of exposure operation, and FIG. 14B is a view (No. 6)showing an operation of the substrate encoder system at the time ofexposure operation.

FIG. 15A is a view (No. 7) showing an operation of the mask encodersystem at the time of exposure operation, and FIG. 15B is a view (No. 7)showing an operation of the substrate encoder system at the time ofexposure operation.

FIG. 16A is a view (No. 8) showing an operation of the mask encodersystem at the time of exposure operation, and FIG. 16B is a view (No. 8)showing an operation of the substrate encoder system at the time ofexposure operation.

FIG. 17 is a planar view showing a substrate holder and a pair of headunits of a substrate encoder system that a liquid crystal exposureapparatus according to a second embodiment has, along with a projectionoptical system.

FIGS. 18A and 18B are views used to explain a movement range in anX-axis direction of the substrate holder when position measurement ofthe substrate holder is performed.

FIGS. 19A to 19D are views used to explain a first state to a fourthstate in a state change of positional relation between a pair of headunits and a scale in the process when the substrate holder moves in theX-axis direction in the second embodiment.

FIGS. 20A to 20C are views used to explain a linkage process at the timeof switching heads of the encoder system that measures positioninformation of the substrate holder performed in the liquid crystalexposure apparatus according to the second embodiment.

FIG. 21 is a planar view showing a substrate holder and a pair of headunits of a substrate encoder system that a liquid crystal exposureapparatus according to a third embodiment has, along with a projectionoptical system.

FIG. 22 is a view used to explain a characteristic structure of a liquidcrystal exposure apparatus according to a fourth embodiment.

DESCRIPTION OF EMBODIMENTS First Embodiment

Hereinafter, a first embodiment will be described, using FIGS. 1 to 16B.

FIG. 1 schematically shows a structure of a liquid crystal exposureapparatus 10 according to the first embodiment. Liquid crystal exposureapparatus 10 is a projection exposure apparatus of a step-and-scanmethod, or a so-called scanner whose exposure target is a rectangular(square-shaped) glass substrate P (hereinafter simply referred to assubstrate P) used in, for example, a liquid crystal display device (flatpanel display) or the like.

Liquid crystal exposure apparatus 10 has an illumination system 12, amask stage device 14 that holds a mask M on which a circuit pattern andthe like is formed, a projection optical system 16, an apparatus mainsection 18, a substrate stage device 20 that holds substrate P whosesurface (a surface facing a +Z side in FIG. 1) is coated with a resist(sensitive agent), a control system for these parts and the like. In thedescription below, a direction in which mask M and substrate P are eachrelatively scanned with respect to an illumination light IL at the timeof scanning exposure within a predetermined plane (XY plane, ahorizontal plane in FIG. 1) orthogonal to an optical axis (coincideswith an optical axis of illumination system 12 in the embodiment) ofprojection optical system 16 will be described as an X-axis direction, adirection orthogonal to the X-axis direction in the horizontal planewill be described as a Y-axis direction, a direction orthogonal to theX-axis and the Y-axis will be described as a Z-axis direction, androtation directions around the X-axis, the Y-axis, and the Z-axis willeach be described as a θx direction, a θy direction, and a θz direction.Also, positions in the X-axis, the Y-axis, and the Z-axis directionswill each be described as an X position, a Y position, and a Z position.

Illumination system 12 is structured similarly to the illuminationsystem disclosed in, for example, U.S. Pat. No. 5,729,331 and the like.Illumination system 12 irradiates mask M with a light emitted from alight source not shown (e.g. a mercury lamp) serving as an exposureillumination light (illumination light) IL, via parts such as areflection mirror, a dichroic mirror, a shutter, a wavelength selectionfilter, and various kinds of lenses. As illumination light IL, forexample, a light including at least one of an i-line (wavelength 365nm), a g-line (wavelength 436 nm), and an h-line (wavelength 405 nm) (inthe embodiment, a synthetic light of the i-line, the g-line, and theh-line described above) is used. Illumination system 12 has a pluralityof optical systems that irradiates a plurality of illumination areaswhose positions in the Y-axis direction are different with illuminationlight IL, and the number of this plurality of optical systems is thesame as the number of a plurality of optical systems of projectionoptical system 16 to be described later on.

Mask stage device 14 includes a mask holder (also called a slider or amovable member) 40 that holds mask M, for example, by vacuum suction, amask drive system 91 (not shown in FIG. 1, refer to FIG. 8) that movesmask holder 40 in a scanning direction (the X-axis direction) inpredetermined long strokes and also finely moves the mask holder in theY-axis direction and the θz direction, and a mask position measurementsystem that measures at least position information (position informationin directions of three degrees of freedom including the X-axisdirection, the Y-axis direction, and the θz direction, and the θzdirection includes rotation (yawing) information) of mask holder 40within the XY plane. Mask holder 40 consists of a frame shaped member inwhich an opening section in a rectangular shape in a planar view isformed, as is disclosed in, for example, U.S. Patent ApplicationPublication No. 2008/0030702. Mask holder 40 is mounted on a pair ofmask guides 42 fixed to an upper mount section 18 a, which is a part ofapparatus main section 18, via, for example, an air bearing (not shown).Mask drive system 91 includes, for example, a linear motor (not shown).While the description below is made with mask holder 40 being moved, atable or a stage having a holding section of mask M may be moved. Thatis, the mask holder holding the mask does not necessarily have to beprovided separately with the mask table or the mask stage and the maskmay be held by vacuum suction or the like on the mask table or the maskstage, and in such a case, the mask table or the mask stage holding themask is to be moved in directions of three degrees of freedom within theXY plane.

The mask position measurement system is equipped with a mask encodersystem 48 that has one of a pair of encoder head units 44 (hereinaftersimply referred to as a head unit 44) and a plurality of encoder scales46 (overlapping in a depth direction of the page surface in FIG. 1,refer to FIG. 3A) irradiated with a measurement beam via head unit 44provided at mask holder 40, and the other of encoder heads 44 and theplurality of encoder scales 46 provided facing mask holder 40. In theembodiment, encoder head 44 is provided at upper mount section 18 a viaan encoder base 43, and the plurality of encoder scales 46 are providedon the lower surface side of mask holder 40 so that the encoder scaleseach face the pair of encoder heads 44. Note that encoder head 44 may beprovided, not at upper mount section 18 a but at, for example, the upperend side of projection optical system 16. The structure of mask encodersystem 48 will be described in detail, later on.

Projection optical system (projection system) 16 is supported by uppermount section 18 a, and is placed below mask stage device 14. Projectionoptical system 16 is a so-called multi-lens projection optical systemhaving a structure similar to the projection optical system disclosedin, for example, U.S. Pat. No. 6,552,775 and the like, and is equippedwith a plurality of (in the embodiment, e.g. 11; refer to FIG. 3A)optical systems (projection optical systems) that form an upright normalimage with a double telecentric equal magnifying system.

In liquid crystal exposure apparatus 10, when an illumination area onmask M is illuminated with illumination light IL from illuminationsystem 12, by the illumination light having passed mask M, a projectionimage (partial upright image) of the circuit pattern of mask M withinthe illumination area is formed on an irradiation area (exposure area)of the illumination light on substrate P conjugate with the illuminationarea, via projection optical system 16. And, by substrate P beingrelatively moved in the scanning direction with respect to the exposurearea (illumination light IL) along with mask M being relatively moved inthe scanning direction with respect to the illumination area(illumination light IL), scanning exposure of a shot area on substrate Pis performed, and the pattern formed on mask M is transferred onto theshot area.

Apparatus main section (also referred to such as a main section or aframe structure) 18 supports mask stage device 14, projection opticalsystem 16, and substrate stage device 20 described above, and isinstalled on a floor 11 of a clean room via a plurality of vibrationisolation devices 19. Apparatus main section 18 is structured similarlyto the apparatus main section disclosed in, for example, U.S. PatentApplication Publication No. 2008/0030702. In the embodiment, theapparatus main section has upper mount section 18 a (also called anoptical surface plate) that supports projection optical system 16described above, a pair of lower mount sections 18 b (one of the lowermount section is not shown in FIG. 1 since the lower mount sections arearranged overlapping in the depth direction of the page surface, referto FIG. 2) where substrate stage device 20 is arranged, and a pair ofmiddle mount sections 18 c.

Substrate stage device 20 is a device used to position substrate P withhigh precision with respect to the plurality of partial images (exposurelight IL) of the mask pattern projected via projection optical system 16in scanning exposure, and moves substrate P in directions of six degreesof freedom (the X-axis, the Y-axis, and the Z-axis directions, and theθx, the θy, and the θz directions). While the structure of substratestage device 20 is not limited in particular, a stage device of aso-called coarse/fine movement structure can be used, including a gantrytype two-dimensional coarse movement stage and a fine movement stagefinely moved with respect to the two-dimensional coarse movement stage,as is disclosed in, for example, U.S. Patent Application Publication No.2008/129762, U.S. Patent Application Publication No. 2012/0057140 andthe like. In this case, substrate P can be moved in directions of threedegrees of freedom within the horizontal plane by the coarse movementstage, and substrate P can also be finely moved in directions of sixdegrees of freedom by the fine movement stage.

FIG. 2 shows an example of substrate stage device 20 of the so-calledcoarse/fine movement structure used in liquid crystal exposure apparatus10 of the embodiment. Substrate stage device 20 is equipped with a pairof base frames 22, a Y coarse movement stage 24, an X coarse movementstage 26, a weight canceling device 28, a Y step guide 30, and a finemovement stage 32.

Base frame 22 consists of a member extending in the Y-axis direction,and is installed on floor 11 in a state vibrationally isolated fromapparatus main section 18. Also, an auxiliary base frame 23 is placed inbetween the pair of lower mount sections 18 b of main section 18. Ycoarse movement stage 24 has a pair of (one of the pair not shown inFIG. 2) X beams 25 laid between the pair of base frames 22. Auxiliarybase frame 23 described earlier supports the center part in thelongitudinal direction of X beam 25 from below. Y coarse movement stage24 is moved in predetermined long strokes in the Y-axis direction on thepair of base frames 22 via a plurality of Y linear motors serving as apart of a substrate drive system 93 (not shown in FIG. 2, refer to FIG.8) that drives substrate P in directions of six degrees of freedom. Xcoarse movement stage 26 is mounted on Y coarse movement stage 24 in astate lying in between the pair of X beams 25. X coarse movement stage26 is moved in predetermined long strokes in the X-axis direction on Ycoarse movement stage 24 via a plurality of X linear motors serving as apart of substrate drive system 93. Also, X coarse movement stage 26 ismechanically limited in relative movement in the Y-axis direction withrespect to Y coarse movement stage 24, and moves in the Y-axis directionintegrally with Y coarse movement stage 24.

Weight canceling device 28 is inserted in between the pair of X beams 25and is also mechanically connected to X coarse movement stage 26. Thisallows weight canceling device 28 to move in predetermined long strokesin the X-axis direction and/or the Y-axis direction integrally with Xcoarse movement stage 26. Y step guide 30 consists of a member extendingin the X-axis direction, and is mechanically connected to Y coarsemovement stage 24. This allows Y step guide 30 to move in predeterminedlong strokes in the Y-axis direction integrally with Y coarse movementstage 24. The above weight canceling device 28 is mounted on Y stepguide 30 via a plurality of air bearings. Weight canceling device 28,when X coarse movement stage 26 moves only in the X-axis direction,moves in the X-axis direction on Y step guide 30 which is in astationary state, and when X coarse movement stage 26 moves in theY-axis direction (including the case when there is also movement in theX-axis direction), weight canceling device 28 moves in the Y-axisdirection integrally with Y step guide 30 (so that the weight cancelingdevice does not fall off from Y step guide 30).

Fine movement stage 32 consists of a plate-shaped (or a box-shaped)member rectangular in a planar view, and the center part is supportedfrom below by weight canceling device 28 in a state freely swingablewith respect to the XY plane via a spherical bearing device 29. Asubstrate holder 34 is fixed to the upper surface of fine movement stage32, and substrate P is mounted on substrate holder 34. Note that thesubstrate holder holding the substrate does not necessarily have to beprovided separately from a table or a stage where the holding sectionthat holds the substrate is provided, in this case, fine movement stage32, and the substrate may be held by vacuum suction or the like on thetable or the stage. Fine movement stage 32 includes a stator that Xcoarse movement stage 26 has and a mover that fine movement stage 32has, and is finely moved in directions of six degrees of freedom withrespect to X coarse movement stage 26 by a plurality of linear motors 33(e.g. voice coil motors) that structures a part of the above substratedrive system 93 (not shown in FIG. 2, refer to FIG. 8). Also, finemovement stage 32 moves in predetermined long strokes in the X-axisdirection and/or the Y-axis direction along with X coarse movement stage26 by thrust given by X coarse movement stage 26 via the plurality oflinear motors 33 above. The structure of substrate stage device 20described so far (however excluding the measurement system) is disclosedin, for example, U.S. Patent Application Publication No. 2012/0057140.

Also, substrate stage device 20 has a substrate position measurementsystem to measure position information in directions of six degrees offreedom of fine movement stage 32 (that is, substrate holder 34 andsubstrate P). The substrate position measurement system, as is shown inFIG. 8, includes a Z-tilt position measurement system 98 to obtainposition information of substrate P in the Z-axis, the θx, and the θydirections (hereinafter referred to as a Z-tilt direction) and asubstrate encoder system 50 to obtain position information in directionsof three degrees of freedom of substrate P within the XY plane. Z-tiltposition measurement system 98, as is shown in FIG. 2, is equipped witha plurality of Z sensors 36, with each Z sensor 36 including a probe 36a attached to the lower surface of fine movement stage 32 and a target36 b attached to weight canceling device 28. The plurality of Z sensors36, e.g. four (at least three), is arranged at a predetermined spacing,for example, around an axis parallel to the Z-axis passing through thecenter of fine movement stage 32. A main controller 90 (refer to FIG. 8)obtains Z position information and rotation amount information in the θxand θy directions of fine movement stage 32, based on an output of theabove plurality of Z sensors 36. The structure of Z-tilt positionmeasurement system 98 including the above z sensors 36 is disclosed indetail in, for example, U.S. Patent Application Publication No.2010/0018950. The structure of substrate encoder system 50 will bedescribed later on.

Next, a structure of mask encoder system 48 will be described, usingFIGS. 3A and 3B. As is shown modeled in FIG. 3A, the plurality ofencoder scales 46 (may also be referred to as a grating member, gratingsection, a grid member or the like, but will be simply referred tohereinafter as scale 46) is arranged in each of an area on the +Y sideand the −Y side of mask M (or to be more specific, an opening sectionnot shown to house mask M) of mask holder 40. Note that to facilitateunderstanding, while the plurality of scales 46 is drawn in solid linesand is illustrated as if the plurality of scales is placed on the uppersurface of mask holder 40 in FIG. 3A, the plurality of scales 46 isactually placed on the lower surface side of mask holder 40 so that theZ position of the lower surfaces of each of the plurality of scales 46coincides with the Z position of the lower surface (pattern surface) ofmask M, as is shown in FIG. 1. The plurality of scales 46 each has agrating area (grating section) in which a reflective two-dimensionalgrating or two reflective one-dimensional gratings with different (e.g.orthogonal) arrangement directions (periodic directions) are formed, andthe plurality of scales 46 is provided at the lower surface side of maskholder 40 on both sides of the mounting area (including the openingsection described earlier) of mask M in the Y-axis direction so that thegrating areas are arranged apart in the X-axis direction. Note thatwhile the grating may be formed to cover the entire area of scales 46 inthe X-axis and the Y-axis directions, since it is difficult to form thegrating with good precision at the edge of scales 46, in the embodiment,the grating is formed so that the periphery of the grating area inscales 46 is to be a margin part. Therefore, spacing between the gratingareas is larger than the spacing between the pair of scales 46 adjacentin the X-axis direction, and the period while an area other than thegrating areas is irradiated with the measurement beam is to be anon-measurement period (also called a non-measurement section; however,hereinafter referred to collectively as non-measurement period) in whichposition measurement cannot be performed.

In mask holder 40 of the embodiment, in the areas on the +Y side and the−Y side of the mounting area of mask M, for example, three scales 46 arearranged in the X-axis direction at a predetermined spacing. That is,mask holder 40 has a total of, for example, six scales 46. Each of theplurality of scales 46 is substantially identical, except for the pointthat the scales are arranged symmetrically in the vertical direction ofthe page surface on the +Y side and the −Y side of mask M. Scale 46consists of a rectangular plate-shaped (strip-shaped) member in a planarview extending in the X-axis direction, made of, for example, quartzglass. Mask holder 40, is formed of, for example, ceramics, and theplurality of scales 46 is fixed to mask holder 40. In the embodiment,instead of the plurality of scales 46 arranged apart in the X-axisdirection, one (single) scale may be used as a mask holder scale. Inthis case, the grating area may also be one, or a plurality of gratingareas may be formed on one scale set apart in the X-axis direction.

As is shown in FIG. 3B, on the lower surface (a surface facing the −Zside in the embodiment) of scale 46 at an area on one side in the widthdirection (the −Y side in FIG. 3B), an X scale 47 x is formed. Also, onthe lower surface of scale 46 at an area on the other side in the widthdirection (the +Y side in FIG. 3B), a Y scale 47 y is formed. X scale 47x is structured by a reflective diffraction grating (an X grating)having a plurality of grid lines extending in the Y-axis directionformed at a predetermined pitch in the X-axis direction (the X-axisdirection serving as a periodic direction). Similarly, Y scale 47 y isstructured by a reflective diffraction grating (a Y grating) having aplurality of grid lines extending in the X-axis direction formed at apredetermined pitch in the Y-axis direction (the Y-axis directionserving as a periodic direction). In X scale 47 x and Y scale 47 y ofthe embodiment, the plurality of grid lines is formed at a spacing of,for example, 10 nm or less. Note that in FIGS. 3A and 3B, forconvenience of illustration, the spacing (pitch) between the grids isshown much wider than the actual spacing. The same applies to otherdrawings as well.

Also, as is shown in FIG. 1, a pair of encoder bases 43 is fixed on theupper surface of upper mount section 18 a. The pair of encoder bases 43has one encoder base arranged on the −X side of mask guide 42 on the +Xside, and the other on the +X side of mask guide 42 on the −X side (thatis, in the area between the pair of mask guides 42). Also, a part ofprojection optical system 16 described above is arranged in between thepair of encoder bases 43. Encoder base 43, as is shown in FIG. 3A,consists of a member extending in the X-axis direction. Encoder headunit 44 (hereinafter simply referred to as head unit 44) is fixed in thecenter in the longitudinal direction of each of the pair of encoderbases 43. That is, head unit 44 is fixed to apparatus main section 18(refer to FIG. 1), via encoder base 43. Since the pair of head units 44is substantially identical, except for the point that the head units arearranged symmetrically in the vertical direction of the page surface onthe +Y side and the −Y side of mask M, the description below is on onlyone of the head units (on the −Y side).

As is shown in FIG. 3B, head unit 44 has a plurality of heads whoseposition of a measurement beam, irradiated on at least one of theplurality of scales 46 arranged in the X-axis direction, is different inat least one of the X-axis direction and the Y-axis direction, and aunit base 45 consisting of a plate-shaped member having a rectangularshape in a planar view. Fixed to unit base 45 are a pair of X heads 49 xarranged separately to each other that irradiates a measurement beam ata spacing larger than the spacing of a pair of X scales 47 x adjacent inthe X-axis direction (grating area), and a pair of Y heads 49 y arrangedseparately to each other that irradiates a measurement beam at a spacinglarger than the spacing of the pair of Y scales 47 y adjacent in theX-axis direction (grating area). That is, mask encoder system 48, forexample, has a total of four X heads 49 x; one pair each on both sidesof the mounting area of mask M of mask holder 40 in the Y-axisdirection, along with a total of four Y heads 49 y; one pair each onboth sides of the mounting area of mask M in the Y-axis direction. Notethat the pair of X heads 49 x or the pair of Y heads 49 y does notnecessarily have to be arranged separate larger than the spacing of thepair of X scales 49 x or the pair of Y scales 49 y, and may be arrangedat a spacing around the same scale spacing or smaller or may be arrangedin contact with each other, as long as a pair of measurement beams isarranged larger than the scale spacing in the X-axis direction. Also, inFIG. 3B, while one of X head 49 x and one of Y head 49 y are housedtogether in a housing and the other of X head 49 x and the other of Yhead 49 y are housed together in another housing, the pair of X heads 49x and the pair of Y heads 49 y may each be arranged independently. Also,in FIG. 3B, to facilitate understanding, while the pair of X heads 49 xand the pair of Y heads 49 y are illustrated to be arranged above (the+Z side) scale 46, the pair of X heads 49 x is actually arranged below Xscale 47 y and the pair of Y heads 49 y is actually arranged below Yscale 47 y (refer to FIG. 1).

The pair of X heads 49 x and the pair of Y heads 49 y are fixed to unitbase 45 so that a position (especially the position in a measurementdirection (the X-axis direction)) of at least one of the pair of X heads49 x (measurement beam) or head (measurement beam) spacing, and aposition (especially the position in a measurement direction (the Y-axisdirection)) of at least one of the pair of Y heads 49 y (measurementbeam) or head (measurement beam) spacing do not change due to, forexample, vibration or the like. Also, unit base 45 itself is also formedof a material whose coefficient of thermal expansion is lower than scale46 (or is about the same as scale 46), so that the position or spacingof the pair of X heads 49 x and the position or spacing of the pair of Yheads 49 y do not change due to, for example, temperature change or thelike.

X head 49 x and Y head 49 y are encoder heads of a so-called diffractioninterference method as is disclosed in, for example, U.S. PatentApplication Publication No. 2008/0094592 that irradiate correspondingscales (X scale 47 x, Y scale 47 y) with measurement beams, and byreceiving the beams from the scales, supply displacement amountinformation of mask holder 40 (namely mask M, refer to FIG. 3A) to maincontroller 90 (refer to FIG. 8). That is, in mask encoder system 48,e.g. four X heads 49 x and X scale 47 x (differs depending on the Xposition of mask holder 40) facing the X heads 49 x structure, e.g. fourX linear encoders 92 x (not shown in FIG. 3B, refer to FIG. 8) forobtaining position information of mask M in the X-axis direction, ande.g. four Y heads 49 y and Y scale 47 y (differs depending on the Xposition of mask holder 40) facing the Y heads 49 y structure, e.g. fourY linear encoders 92 y (not shown in FIG. 3B, refer to FIG. 8) forobtaining position information of mask M in the Y-axis direction. In theembodiment, while a head is used whose measurement direction is in oneof two different directions (coincides with the X-axis direction and theY-axis direction) within the XY plane, a head may be used whosemeasurement direction differs from one of the X-axis direction and theY-axis direction. For example, a head may be used whose measurementdirection is in a direction rotated by an angle of 45 degrees withrespect to the X-axis direction or the Y-axis direction within the XYplane. Also, instead of a one-dimensional head (an X head or a Y head)whose measurement direction is in one of the two different directionswithin the XY plane, for example, a two-dimensional head (an XZ head ora YZ head) whose measurement direction is in two directions such as; oneof the X-axis direction and the Y-axis direction, and the Z-axisdirection, may be used. In this case, it also becomes possible tomeasure position information of mask holder 40 in directions of threedegrees of freedom (including the Z-axis direction, the θx direction,and the θy direction, and θx direction is rolling information, θydirection is pitching information) different from the directions ofthree degrees of freedom described above (the X-axis direction, theY-axis direction, and the θz direction).

Main controller 90, as is shown in FIG. 8, obtains position informationof mask holder 40 (refer to FIG. 3A) in the X-axis direction and theY-axis direction, based on an output of, e.g. four X linear encoders 92x, and e.g. four Y linear encoders 92 y, at a resolution of, forexample, 10 nm or less. Also, main controller 90 obtains θz positioninformation (rotation amount information) of mask holder 40, forexample, based on an output of at least two of the four X linearencoders 92 x (or e.g. four Y linear encoders 92 y). Main controller 90controls the position in the XY plane of mask holder 40 using mask drivesystem 91, based on position information in directions of three degreesof freedom within the XY plane of mask holder 40 obtained frommeasurement values of mask encoder system 48 described above.

Here, as is shown in FIG. 3A, in mask holder 40 as is described above,in each of the areas on the +Y side and the −Y side of mask M, forexample, three scales 46 are arranged in the X-axis direction at apredetermined spacing. Also, at least in scanning exposure of substrateP, of the e.g. three scales 46 arranged in the X-axis direction at apredetermined spacing described above, mask holder 40 is moved in theX-axis direction between a position where head unit 44 (all the pair ofX heads 49 x and the pair of Y heads 49 y (each refer to FIG. 3B)) facesscale 46 furthest to the +X side and a position where head unit 44 facesscale 46 furthest to the −X side. Note that in at least one of anexchange operation and a pre-alignment operation of mask M, in the casemask holder 40 is moved away from the illumination area illuminated withillumination light IL in the X-axis direction and at least one head ofhead unit 44 moves off of scale 46, at least one head arranged away fromhead unit 44 may be provided in the X-axis direction so that positionmeasurement of mask holder 40 by mask encoder system 48 can be continuedeven in the exchange operation or the pre-alignment operation.

And, in mask stage device 14 of the embodiment, as is shown in FIG. 3B,the spacing between each of the pair of X heads 49 x and the pair of Yheads 49 y that one head unit 44 has is set larger than a pair of scales46 adjacent to each other of the plurality of scales 46. This allows atleast one head of the pair of X heads 49 x to constantly face X scale 47x and at least one head of the pair of Y heads 49 y to constantly face Yscale 47 y in mask encoder system 48. Accordingly, mask encoder system48 can supply position information of mask holder 40 (refer to FIG. 3A)to main controller 90 (refer to FIG. 8) without the position informationbeing cut off.

To describe this specifically, for example, in the case mask holder 40(refer to FIG. 3A) moves to the +X side, mask encoder system 48 goesthrough; a first state (the state shown in FIG. 3B) in which the pair ofheads 49 x both face X scale 47 x on the +X side of the adjacent pair ofX scales 47 x, a second state in which X head 49 x on the −X side facesan area between the above adjacent pair of X scales 47 x (facing neitherof the X scales 47 x) and X head 49 x on the +X side faces X scale 47 xon the +X side, a third state in which X head 49 x on the −X side facesX scale 47 x on the −X side and X head 49 x on the +X side faces X scale47 x on the +X side, a fourth state in which X head 49 x on the −X sidefaces X scale 47 x on the −X side and X head 49 x on the +X side facesan area between a pair of X scales 47 x (facing neither of the X scales47 x), and a fifth state in which the pair of heads 49 x both face Xscale 47 x on the −X side, in the order described above. Accordingly, atleast one of the X heads 49 x constantly faces X scale 47 x.

Main controller 90 (refer to FIG. 8), in the first state, the thirdstate, and the fifth state described above, obtains X positioninformation of mask holder 40, based on an average value of the outputof the pair of X heads 49 x. Also, main controller 90, in the secondstate described above, obtains X position information of mask holder 40,based on only the output of X head 49 x on the +X side, and in thefourth state described above, obtains X position information of maskholder 40, based on only the output of X head 49 on the −X side.Accordingly, measurement values of mask encoder system 48 are not cutoff. Note that the X position information may also be obtained using theoutput of only one of the pair of X heads 49 x also in the first state,the third state, and the fifth state. However, in the second state andthe fourth state, in both the pair of head units 44 one of the pair of Xheads 49 x and one of the Y heads 49 y move off of scale 46 so thatposition information in the θz direction (rotation information) of maskholder 40 can no longer be acquired. Therefore, it is preferable toarrange the three scales 46 arranged on the +Y side and the three scales46 arranged on the −Y side with respect to the mounting area of mask Mshifted from one another so that the spacing between adjacent pair ofscales 46 do not overlap in the X-axis direction, and that even when Xhead 49 x and Y head 49 y move off of scale 46 in one of the threescales 46 arranged on the +Y side and the three scales 46 arranged onthe −Y side, X head 49 x and Y head 49 y do not move off in the other ofthe scales 46. Or, the pair of head units 44 may be arranged shifted inthe X-axis direction only by a distance larger than the spacing of anadjacent pair of scales 46 (width in a non-grating area). This avoidsthe non-measurement period when measurement beams move off (cannotmeasure) the grating area of scale 46 in the X-axis direction fromoverlapping in a total of four heads; the pair of X heads 49 x arrangedon the +Y side and the pair of X heads 49 x arranged on the −Y side, andmakes it possible to constantly measure position information in the θzdirection of mask holder 40 at least during scanning exposure. Note thatin at least one of the pair of head units 44, at least one head may bearranged which is arranged apart in the X-axis direction with respect toat least one of the pair of X heads 49 x and the pair of Y heads 49 y,so that two heads face scale 46 in at least one of X head 49 x and Yhead 49 y, also in the second state and in the fourth state.

Next, the structure of substrate encoder system 50 will be described.Substrate encoder system 50, as is shown in FIG. 1, is equipped with aplurality of encoder scales 52 (overlapping in the depth of the pagesurface in FIG. 1, refer to FIG. 4A) arranged at substrate stage device20, an encoder base 54 fixed to the lower surface of upper mount section18 a, a plurality of encoder scales 56 fixed to the lower surface ofencoder base 54, and a pair of encoder head units 60.

As is shown modeled in FIG. 4A, in substrate stage device 20 of theembodiment, in an area on the +Y side and on the −Y side of substrate P(substrate mounting area), for example, five encoder scales 52(hereinafter simply referred to as scales 52) are arranged at apredetermined spacing in the X-axis direction. That is, substrate stagedevice 20 has a total of, for example, 10 scales 52. Each of theplurality of scales 52 is substantially identical, except for the pointthat the scales are arranged symmetrically in the vertical direction ofthe page surface on the +Y side and the −Y side of substrate P. Scale52, similarly to scale 46 (each refer to FIG. 3A) of mask encoder system48 described above, consists of a rectangular plate-shaped(strip-shaped) member in a planar view extending in the X-axisdirection, made of, for example, quartz glass. Also, the plurality ofscales 52 each has a grating area (grating section) in which areflective two-dimensional grating or two reflective one-dimensionalgratings with different (e.g. orthogonal) arrangement directions(periodic directions) are formed, and five scales 52 are provided onboth sides of the substrate mounting area in the Y-axis direction sothat the grating areas are arranged apart in the X-axis direction.

Note that in FIGS. 1 and 4A, to facilitate understanding, while theplurality of scales 52 is illustrated as if the plurality of scales isfixed to the upper surface of substrate holder 34, the plurality ofscales 52 as is shown in FIG. 2 is actually fixed (note that in FIG. 2,a case is illustrated in which the plurality of scales 52 is arranged onthe +X side and the −X side of substrate P) to fine movement stage 32via scale base 51 in a state set apart from substrate holder 34.However, depending on the case, the plurality of scales 52 may actuallybe fixed to substrate holder 34. In the description below, the pluralityof scales 52 will be described as being arranged on substrate holder 34.Note that the plurality of scales 52 may be arranged on an upper surfaceof a substrate table that has substrate holder 34 and can be finelydrive in at least the Z-axis direction, the θx direction, and the θydirection, or on an upper surface of a substrate stage that supports thesubstrate table in a finely movable manner.

As is shown in FIG. 4B, in an area on one side of the width direction(−Y side in FIG. 4B) on the upper surface of scale 52, an X scale 53 xis formed. Also, in an area on the other side of the width direction (+Yside in FIG. 4B) on the upper surface of scale 52, a Y scale 53 y isformed. Since the structure of X scale 53 x and Y scale 53 y is similarto X scale 47 x and Y scale 47 y (each refer to FIG. 3B) formed on scale46 (each refer to FIG. 3A) of mask encoder system 48 described above,the description thereabout will be omitted.

Encoder base 54, as it can be seen from FIGS. 5 and 6, is equipped witha first part 54 a consisting of a plate-shaped member extending in theY-axis direction fixed to the lower surface of upper mount section 18 a,and a second part 54 b consisting of a member having a U-shaped XZ crosssectional surface extending in the Y-axis direction fixed to the lowersurface of the first part 54 a, and is formed in a cylindrical shapeextending in the Y-axis direction as a whole. As is shown in FIG. 4A,while the X position of encoder base 54 substantially coincides with theX position of the center of projection optical system 16, encoder base54 and projection optical system 16 are arranged so as not to be incontact with each other. Note that encoder base 54 may be arrangedseparately from projection optical system 16, on the +Y side and the −Yside. To the lower surface of encoder base 54, a pair of Y linear guides63 a is fixed, as is shown in FIG. 6. The pair of Y linear guides 63 aeach consists of a member extending in the Y-axis direction, and isarranged parallel to each other in the X-axis direction at apredetermined spacing.

To the lower surface of encoder base 54, the plurality of encoder scales56 (hereinafter simply referred to as scale 56) is fixed. In theembodiment, as is shown in FIG. 1, scales 56 are arranged each spacedapart in the Y-axis direction; e.g. two in an area further to the +Yside of projection optical system 16, and e.g. two in an area further tothe −Y side of projection optical system 16. That is, to encoder base54, a total of, e.g. four scales 56 are fixed. The plurality of scales56 is each substantially identical. Scale 56 consists of a rectangularplate-shaped (strip-shaped) member in a planar view extending in theY-axis direction, and is made of, for example, quartz glass, similarlyto scale 52 arranged at substrate stage device 20. The plurality ofscales 56 each has a grating area (grating section) in which areflective two-dimensional grating or two reflective one-dimensionalgratings with different (e.g. orthogonal) arrangement directions(periodic directions) are formed, and in the embodiment, similarly toscales 46 and scales 52, two scales 56, each having an X scale with aone-dimensional grating whose arrangement direction (periodic direction)is in the X-axis direction and a Y scale with a one-dimensional gratingwhose arrangement direction (periodic direction) is in the Y-axisdirection, are provided on both sides of projection optical system 16 inthe Y-axis direction so that the grating areas are arranged apart in theY-axis direction. Note that to facilitate understanding, while theplurality of scales 56 is drawn in solid lines and is illustrated as ifthe plurality of scales is placed on the upper surface of encoder base54 in FIG. 4A, the plurality of scales 56 is actually placed on thelower surface side of encoder base 54, as is shown in FIG. 1. Note thatwhile two scales 56 are provided on each of the +Y side and the −Y sideof projection optical system 16 in the embodiment, the number of scales56 provided may be not two, but one or three, or more than three. Also,while scales 56 are provided so that the grating surface faces downward(the grating area becomes parallel to the XY plane) in the embodiment,for example, scales 56 may be provided so that the grating area becomesparallel to the YZ plane.

As is shown in FIG. 4C, in an area on one side of the width direction(+X side in FIG. 4C) on the lower surface of scale 56, an X scale 57 xis formed. Also, at the lower surface of scale 56 at an area on theother side in the width direction (the −X side in FIG. 4C), a Y scale 57y is formed. Since the structure of X scale 57 x and Y scale 57 y issimilar to X scale 47 x and Y scale 47 y (each refer to FIG. 3B) formedon scale 46 (each refer to FIG. 3A) of mask encoder system 48 describedabove, the description thereabout will be omitted.

Referring back to FIG. 1, the pair of encoder head units 60 (hereinaftersimply referred to as a head unit 60) is arranged below encoder base 54spaced apart in the Y-axis direction. Since the pair of head units 60 iseach substantially identical, except for the point that the head unitsare arranged symmetrically in the horizontal direction of the pagesurface in FIG. 1, the description below is on only one of the headunits (on the −Y side). Head unit 60, as is shown in FIG. 5, is equippedwith a Y slide table 62, a pair of X heads 64 x, a pair of Y heads 64 y(not shown in FIG. 5 because of being hidden behind the pair of X heads64 x in the depth of the page surface, refer to FIG. 4C), a pair of Xheads 66 x (one of the X heads 66 x not shown in FIG. 5, refer to FIG.4B), a pair of Y heads 66 y (one of the Y heads 66 y not shown in FIG.5, refer to FIG. 4B), and a belt driver 68 that moves Y slide table 62in the Y-axis direction. Note that the pair of head units 60 in theembodiment has the same structure as the pair of head units 44 of maskencoder system 48, except for the point that the pair of head units 60is rotated by an angle of 90 degrees.

Y slide table 62 consists of a rectangular plate-shaped member in aplanar view, and is arranged below encoder base 54 via a predeterminedclearance with respect to encoder base 54. Also, the Z position of Yslide table 62 is to be set further to the +Z side than substrate holder34, regardless of the Z-tilt position of substrate holder 34 thatsubstrate stage device 20 has (each refer to FIG. 1).

To the upper surface of Y slide table 62, as is shown in FIG. 6, aplurality of Y slide members 63 b is fixed that engages freely slidablein the Y-axis direction with respect to Y linear guides 63 a describedabove (e.g. two (refer to FIG. 5) with respect to one Y linear guide 63a), via a rolling body (e.g. a plurality of balls) (not shown). Y linearguide 63 a and Y slide member 63 b corresponding to Y linear guide 63 astructure a mechanical Y linear guide device 63 as is disclosed in, forexample, U.S. Pat. No. 6,761,482, and Y slide table 62 is straightlyguided in the Y-axis direction with respect to encoder base 54 via thepair of Y linear guide devices 63.

Belt driver 68, as is shown in FIG. 5, is equipped with a rotary driver68 a, a pulley 68 b, and a belt 68 c. Note that belt driver 68 may bearranged independently for driving Y slide table 62 on the −Y side andfor driving Y slide table 62 on the +Y side (not shown in FIG. 5, referto FIG. 4A), or the pair of Y slide table 62 may be moved integrally byone belt driver 68.

Rotary driver 68 a is fixed to encoder base 54, and is equipped with arotary motor (not shown). The number of rotation and the rotationdirection of the rotary motor are controlled by main controller 90(refer to FIG. 8). Pulley 68 b is rotationally moved around an axisparallel to the X-axis by rotary driver 68 a. Also, although it is notshown, belt driver 68 has another pulley attached to encoder base 54,arranged separate in the Y-axis direction with respect to pulley 68 bdescribed above, in a state freely rotatable around the axis parallel tothe X-axis. Belt 68 c has one end and the other end connected to Y slidetable 62, and two places in the middle part of the longitudinaldirection are wound around pulley 68 b and the another pulley (notshown) described above in a state where a predetermined tension isapplied. A part of belt 68 c is inserted into encoder base 54, and forexample, dust from belt 68 c is kept from adhering on scales 52 and 56.Y slide table 62 moves back and forth in predetermined strokes in theY-axis direction by being pulled by belt 68 c, by pulley 68 b beingrotationally moved.

Main controller 90 (refer to FIG. 8) synchronously moves one of the headunits 60 (on the +Y side) below, e.g. two scales 56 arranged further tothe +Y side than projection optical system 16 and the other of the headunits 60 (on the −Y side) below, e.g. two scales 56 arranged further tothe −Y side of projection optical system 16 in predetermined strokes inthe Y-axis direction, as appropriate. Here, while the pair of head units60 can each be moved synchronously with the movement of substrate stagedevice 20 in the Y-axis direction, in the embodiment, the pair of headunits 60 is to be moved so that with each of the pair of head units 60,measurement beams of the pair of X heads 66 x and the pair of Y heads 66y all do not move off of the grating area of scale 52 (irradiation of agrating area with at least one measurement beam is maintained) in theY-axis direction. Note that in the embodiment, while belt driver 68including pulley 68 b with teeth and belt 68 c with teeth is used as theactuator for moving Y slide table 62, the embodiment is not limited tothis, and a friction wheel device including a pulley and a belt withoutteeth may also be used. Also, the flexible member pulling Y slide table62 is not limited to a belt, and may also be a rope, a wire, or a chain.Also, the type of actuator moving Y slide table 62 is not limited tobelt driver 68, and may also be other drivers such as a linear motor, ora feed screw device.

X head 64 x, Y head 64 y (not shown in FIG. 5, refer to FIG. 6), X head66 x, and Y head 66 y are each an encoder head of a so-calleddiffraction interference method similar to X head 49 x and Y head 49 ythat mask encoder system 48 described above has, and are fixed to Yslide table 62. Here, in head unit 60, the pair of Y heads 64 y, thepair of X heads 64 x, the pair of Y heads 66 y and the pair of X heads66 x are fixed to Y slide table 62 so that the distance between each ofthe heads do not change due to, for example, vibration or the like.Also, Y slide table 62 itself is formed of a material whose coefficientof thermal expansion is lower than scales 52 and 56 (or is about thesame as scales 52 and 56), so that the distance between each of the pairof Y heads 64 y, the pair of X heads 64 x, the pair of Y heads 66 y andthe pair of X heads 66 x do not change due to, for example, temperaturechange or the like.

As is shown in FIG. 7, the pair of X heads 64 x each irradiate twoplaces (two points) separate in the Y-axis direction on X scale 57 xwith a measurement beam, and the pair of Y heads 64 y each irradiate twoplaces (two points) separate in the Y-axis direction on Y scale 57 ywith a measurement beam. Substrate encoder system 50, by receiving thebeams from the scales to which X heads 64 x and Y heads 64 y describedabove correspond, supplies displacement amount information of Y slidetable 62 (not shown in FIG. 7, refer to FIGS. 5 and 6) to maincontroller 90 (refer to FIG. 8). That is, in substrate encoder system50, e.g. four X heads 64 x and X scale 57 x (differs depending on the Yposition of Y slide table 62) facing the X heads 64 x structure, e.g.four X linear encoders 96 x (not shown in FIG. 7, refer to FIG. 8) forobtaining position information of each of the pair of Y slide tables 62(that is, the pair of head units 60 (refer to FIG. 1)) in the Y-axisdirection, and e.g. four Y heads 64 y and Y scale 57 y (differsdepending on the Y position of Y slide table 62) facing the Y heads 64 ystructure, e.g. four Y linear encoders 96 y (not shown in FIG. 7, referto FIG. 8) for obtaining position information of each of the pair of Yslide tables 62 in the Y-axis direction.

Main controller 90, as is shown in FIG. 8, obtains position informationof the pair of head units 60 (refer to FIG. 1) in the X-axis directionand the Y-axis direction, based on an output of, e.g. four X linearencoders 96 x, and e.g. four Y linear encoders 96 y, at a resolution of,for example, 10 nm or less. Also, main controller 90 obtains θz positioninformation (rotation amount information) of one of the head units 60,based on an output of, for example, two X linear encoders 96 x (or forexample, two Y linear encoders 96 y) corresponding to the one head unit60, and obtains θz position information (rotation amount information) ofthe other of the head units 60, based on an output of, for example, twoX linear encoders 96 x (or for example, two Y linear encoders 96 y)corresponding to the other of the head units 60, respectively. Maincontroller 90, based on position information of each of the pair of headunits 60 in the XY plane, controls the position in the Y-axis directionof head unit 60, using belt driver 68.

Here, as is shown in FIG. 4A, in encoder base 54, scale 56, as isdescribed above, in each of the areas on the +Y side and the −Y side ofprojection optical system 16, for example, two scales 56 are arranged inthe Y-axis direction at a predetermined spacing. Also, of the e.g. twoscales 56 arranged in the Y-axis direction at a predetermined spacingdescribed above, Y slide table 62 is moved in the Y-axis direction inbetween a position where head unit 60 (all the pair of X heads 64 x andthe pair of Y heads 64 y (each refer to FIG. 4C)) faces scale 56 on the+Y side and a position where head unit 60 faces scale 56 on the −Y side.

And, similarly to mask encoder system 48 described above, also insubstrate encoder system 50, as is shown in FIG. 4C, the spacing betweeneach of the pair of X heads 64 x and the pair of Y heads 64 y that onehead unit 60 has is set larger than scales 56 adjacent to each other.This allows at least one head of the pair of X heads 64 x to constantlyface X scale 57 x and at least one head of the pair of Y heads 64 y toconstantly face Y scale 57 y in substrate encoder system 50.Accordingly, substrate encoder system 50 can obtain position informationof Y slide table 62 (head unit 60) without the measurement values beingcut off.

Also, as is shown in FIG. 7, the pair of X heads 66 x each irradiatestwo places (two points) separate in the X-axis direction on X scale 53 xwith a measurement beam, and the pair of Y heads 66 y each irradiatestwo places (two points) separate in the X-axis direction on Y scale 53 ywith a measurement beam. Substrate encoder system 50, by receiving thebeams from the scales to which X heads 66 x and Y heads 66 y describedabove correspond, supplies displacement amount information of substrateholder 34 (not shown in FIG. 7, refer to FIG. 2) to main controller 90(refer to FIG. 8). That is, in substrate encoder system 50, e.g. four Xheads 66 x and X scale 53 x (differs depending on the X position ofsubstrate holder 34) facing the X heads 66 x structure, e.g. four Xlinear encoders 94 x (not shown in FIG. 7, refer to FIG. 8) forobtaining position information of substrate P in the X-axis direction,and e.g. four Y heads 66 y and Y scale 53 y (differs depending on the Xposition of substrate holder 34) facing the Y heads 66 y structure, e.g.four Y linear encoders 94 y (not shown in FIG. 7, refer to FIG. 8) forobtaining position information of substrate P in the Y-axis direction.

Main controller 90, as is shown in FIG. 8, obtains position informationof substrate holder 34 (refer to FIG. 2) in the X-axis direction and theY-axis direction, based on an output of, e.g. four X linear encoders 94x, and e.g. four Y linear encoders 94 y, and an output of, e.g. four Xlinear encoders 96 x, and e.g. four Y linear encoders 96 y describedabove (that is, position information of each of the pair of head units60 in the XY plane), at a resolution of, for example, 10 nm or less.Also, main controller 90 obtains θz position information (rotationamount information) of substrate holder 34, for example, based on anoutput of at least two of the four X linear encoders 94 x (or e.g. fourY linear encoders 94 y). Main controller 90 controls the position in theXY plane of substrate holder 34 using substrate drive system 93, basedon position information in the XY plane obtained from measurement valuesof substrate encoder system 50 described above.

Also, as is shown in FIG. 4A, in substrate holder 34, as is describedabove, in each of the areas on the +Y side and the −Y side of substrateP, for example, five scales 52 are arranged in the X-axis direction at apredetermined spacing. Also, of the e.g. five scales 52 arranged in theX-axis direction at a predetermined spacing described above, substrateholder 34 is moved in the X-axis direction between a position where headunit 60 (all the pair of X heads 66 x and the pair of Y heads 66 y (eachrefer to FIG. 4B)) faces scale 52 furthest to the +X side and a positionwhere head unit 60 faces scale 52 furthest to the −X side.

And, similarly to mask encoder system 48 described above, as is shown inFIG. 4B, the spacing between each of the pair of X heads 66 x and thepair of Y heads 66 y that one head unit 60 has is set larger than scales52 adjacent to each other. This allows at least one head of the pair ofX heads 66 x to constantly face X scale 53 x and at least one head ofthe pair of Y heads 66 y to constantly face Y scale 53 y in substrateencoder system 50. Accordingly, substrate encoder system 50 can obtainposition information of substrate holder 34 (refer to FIG. 4A) withoutthe measurement values being cut off.

Note that as for the pair of Y heads 64 y, the pair of X heads 64 x, thepair of Y heads 66 y, and the pair of X heads 66 x that the pair of headunits 60 of substrate encoder system 50 each has and scales 56 and 52irradiated with the measurement beam from these heads, the structureexplained in the whole description (including the explanatory notes)regarding the heads and the scales that structure mask encoder system 48described earlier can be similarly applied.

Referring back to FIG. 6, a dust cover 55 consists of a member extendingin the Y-axis direction that has a U shape formed in the XZ section, andbetween a pair of opposing surfaces, the second part 54 b of encoderbase 54 and Y slide table 62 described above are inserted via apredetermined clearance. In the lower surface of dust cover 55, anopening section is formed through which X head 66 x and Y head 66 y canpass. This keeps dust generated from Y linear guide device 63, belt 68 cand the like from adhering on scale 52. Also, to the lower surface ofencoder base 54, a pair of dust-proof plates 55 a (not shown in FIG. 5)is fixed. Scale 56 is arranged in between the pair of dust-proof plates55 a, which keeps dust generated from Y linear guide device 63 and thelike from adhering on scale 56.

FIG. 8 shows a block diagram of an input/output relation of maincontroller 90 that mainly structures the control system of liquidcrystal exposure apparatus 10 (refer to FIG. 1) having overall controlover each section. Main controller 90 includes a workstation (or amicrocomputer) and the like, and has overall control over each sectionthat structures liquid crystal exposure apparatus 10.

In liquid crystal exposure apparatus 10 (refer to FIG. 1) structured inthe manner described above, substrate P is loaded onto substrate stagedevice 20 (substrate holder 34) by a substrate loader (not shown), alongwith mask M being loaded onto mask stage device 14 by a mask loader (notshown), under the control of main controller 90 (refer to FIG. 8). Then,main controller 90 executes alignment measurement (detection of aplurality of alignment marks on substrate P) using an alignmentdetection system (not shown), and after the alignment measurement hasbeen completed, exposure operation by the step-and-scan method isperformed sequentially on the plurality of shot areas set on substrateP. Note that position information of substrate holder 34 is measured bysubstrate encoder system 50 also in the alignment measurement operation.

Next, an example of an operation of mask stage device 14 and substratestage device 20 during the exposure operation will be described, usingFIGS. 9A to 16B. Note that in the description below, while the case ofsetting four shot areas on one substrate P (a so-called four-piecesetting) is to be described, the number and arrangement of shot areasset on one substrate P can be appropriately changed.

FIG. 9A shows mask stage device 14 after completing the alignmentoperation, and FIG. 9B shows substrate stage device 20 after completingthe alignment operation (however, members other than substrate holder 34is not shown, the same hereinafter). The exposure processing, as anexample, is performed from a first shot area S₁ set on the −Y side andalso on the +X side of substrate P, as is shown in FIG. 9B. With maskstage device 14, as is shown in FIG. 9A, mask M is positioned based onthe output of mask encoder system 48 (refer to FIG. 8), so that the edgeon the +X side of mask M is positioned slightly to the −X side than anillumination area (however, in the state shown in FIG. 9A, mask M is notyet irradiated with illumination light IL) irradiated with illuminationlight IL (each refer to FIG. 1) from illumination system 12.Specifically, for example, scale 46 is provided so that the edge on the+X side of the pattern area of mask M is arranged to be positioned tothe −X side only by an entrance length (that is, an accelerationdistance required to reach a predetermined speed) required to performscanning exposure at a predetermined speed with respect to theillumination area, and that the position of mask M can be measured bymask encoder system 48 at this position. Also, in substrate stage device20, as is shown in FIG. 9B, substrate P is positioned based on theoutput of substrate encoder system 50 (refer to FIG. 8), so that theedge on the +X side of the first shot area S1 is positioned slightly tothe −X side than an exposure area (however, in the state shown in FIG.9B, substrate P is not yet irradiated with illumination light IL)irradiated with illumination light IL (refer to FIG. 1) from projectionoptical system 16. Specifically, for example, scale 52 is provided sothat the edge on the +X side of the first shot area S1 of substrate P isarranged to be positioned to the −X side only by an entrance length(that is, an acceleration distance required to reach a predeterminedspeed) required to perform scanning exposure at a predetermined speedwith respect to the exposure area, and that the position of substrate Pcan be measured by substrate encoder system 50 at this position. Notethat also when mask M and substrate P are each decelerated havingcompleted the scanning exposure of the shot area, scales 46 and 52 areprovided similarly so that the position of mask M and substrate P can bemeasured by mask encoder system 48 and substrate encoder system 50,respectively, until mask M and substrate P are moved further only by adeceleration distance required to decelerate the speed from the speed atthe time of scanning exposure to a predetermined speed. Note that alsowhen mask M and substrate P are each decelerated having completed thescanning exposure of the shot area, scales 46 and 52 are providedsimilarly so that the position of mask M and substrate P can be measuredby mask encoder system 48 and substrate encoder system 50, respectively,until mask M and substrate P are moved further only by a decelerationdistance required to decelerate the speed from the speed at the time ofscanning exposure to a predetermined speed.

Next, as is shown in FIG. 10A, along with mask holder 40 being moved(acceleration, constant speed drive, and deceleration) in the +Xdirection, substrate holder 34 is moved (acceleration, constant speeddrive, and deceleration) in the +X direction synchronously with maskholder 40, as is shown in FIG. 10B. When mask holder 40 is moved, maincontroller 90 (refer to FIG. 8) performs position control of substrate Pbased on the output of substrate encoder system 50 (refer to FIG. 8),along with performing position control of mask M based on the output ofmask encoder system 48 (refer to FIG. 8). When substrate holder 34 ismoved in the X-axis direction, the pair of head units 60 is to be in astationary state. While mask holder 40 and substrate holder 34 are movedat a constant speed in the X-axis direction, illumination light ILhaving passed through mask M and projection optical system 16 (eachrefer to FIG. 1) is irradiated on substrate P, and by this operation,the mask pattern that mask M has is transferred onto shot area S₁.

When transfer of the mask pattern with respect to the first shot area S₁on substrate P has been completed, in substrate stage device 20, as isshown in FIG. 11B, substrate holder 34 is moved (Y step) in the −Ydirection by a predetermined distance (about half the distance of thedimension in the width direction of substrate P) for exposure of asecond shot area S₂ set on the +Y side of the first shot area S₁, basedon the output of substrate encoder system 50 (refer to FIG. 8). In the Ystepping operation of substrate holder 34 described above, mask holder40, as is shown in FIG. 11A, is stationary, in a state where the edge ofmask M on the −X side is positioned slightly to the +X side than theposition of illumination area (however, mask M is not illuminated in thestate shown in FIG. 11A).

Here, as is shown in FIG. 11B, in the Y stepping operation of substrateholder 34 described above, in substrate stage device 20, the pair ofhead units 60 is moved in the Y-axis direction synchronously withsubstrate holder 34. That is, of substrate encoder system 50 (refer toFIG. 8), main controller 90 (refer to FIG. 8) moves the pair of headunits 60 in the Y-axis direction via the corresponding belt driver 68(refer to FIG. 8), based on the output of Y linear encoder 96 y (referto FIG. 8), while moving substrate holder 34 to a target position viasubstrate drive system 93 (refer to FIG. 8), based on the output of Ylinear encoder 94 y. On this operation, main controller 90 moves thepair of head units 60 synchronously with substrate holder 34 (so thatthe pair of head units 60 follow substrate holder 34). Accordingly,measurement beams irradiated from X head 66 and Y head 66 y (each referto FIG. 7) do not move off of X scale 53 x and Y scale 53 y (each referto FIG. 7), regardless of the Y position of substrate holder 34(including while substrate 34 is being moved). In other words, the pairof head units 60 and substrate holder 34 should be moved in the Y-axisdirection around a level in which each of the measurement beamsirradiated from X head 66 x and Y head 66 y while substrate holder 34 isbeing moved in the Y-axis direction (during the Y stepping operation) donot move off of X scale 53 x and Y scale 53 y, that is, around a levelin which measurement from X head 66 x and Y head 66 y using themeasurement beams is not cut off (measurement can be continued). Thatis, the movement of the pair of head units 60 and substrate holder 34 inthe Y-axis direction does not have to be synchronous, or a follow-upmovement.

When the Y stepping operation of substrate holder 34 is completed, alongwith mask holder 40 being moved in the −X direction based on the outputof mask encoder system 48 (refer to FIG. 8) as is shown in FIG. 12A,substrate holder 34 is moved in the −X direction based on the output ofsubstrate encoder system 50 (refer to FIG. 8) synchronously with maskholder 40 as is shown in FIG. 12B. By this operation, the mask patternis transferred onto the second shot area S₂. The pair of head units 60is in a stationary state also on this operation.

When exposure operation of the second shot area S₂ has been completed,in mask stage device 14, as is shown in FIG. 13A, mask holder 40 ismoved in the +X direction, and the position of mask M is set based onthe output of mask encoder system 48 (refer to FIG. 8) so that the edgeon the −X side of mask M is set slightly to the +X side of theillumination area. Also, in substrate stage device 20, as is shown inFIG. 13B, substrate holder 34 is moved in the +X direction for exposureof a third shot area S₃ set on the −X side of the second shot area S₂,and the position of substrate P is set based on the output of substrateencoder system 50 (refer to FIG. 8) so that the edge on the −X side ofthe third shot area S₃ is set slightly to the +X side of the exposurearea. At the time of movement operation of mask holder 40 and substrateholder 34 shown in FIGS. 13A and 13B, illumination system 12 (refer toFIG. 1) does not irradiate mask M (refer to FIG. 13A) and substrate P(refer to FIG. 13B) with illumination light IL. That is, the movementoperation of mask holder 40 and substrate holder 34 shown in FIGS. 13Aand 13B are simply positioning operations (X stepping operations) ofmask M and substrate P.

When the X stepping operations of mask M and substrate P are completed,in mask stage device 14, along with mask holder 40 being moved in the −Xdirection based on the output of mask encoder system 48 (refer to FIG.8) as is shown in FIG. 14A, substrate holder 34 is moved in the −Xdirection based on the output of substrate encoder system 50 (refer toFIG. 8) synchronously with mask holder 40 as is shown in FIG. 14B. Bythis operation, the mask pattern is transferred onto the third shot areaS₃. The pair of head units 60 is in a stationary state also on thisoperation.

When exposure operation of the third shot area S₃ has been completed, insubstrate stage device 20, as is shown in FIG. 15B, substrate holder 34is moved (Y stepping operation) in the +Y direction by a predetermineddistance, for exposure of a fourth shot area S₄ set on the −Y side ofthe third shot area S₃. On this operation, similarly to the time of Ystepping operation of substrate holder 34 shown in FIG. 11B, mask holder40 is to be in a stationary state (refer to FIG. 15A). Also, the pair ofhead units 60 is moved in the +Y direction synchronously with substrateholder 34 (so that the pair of head units 60 follow substrate holder34).

When the Y stepping operation of substrate holder 34 is completed, alongwith mask holder 40 being moved in the +X direction based on the outputof mask encoder system 48 (refer to FIG. 8) as is shown in FIG. 16A,substrate holder 34 is moved in the +X direction based on the output ofsubstrate encoder system 50 (refer to FIG. 8) synchronously with maskholder 40 as is shown in FIG. 16B. By this operation, the mask patternis transferred onto the fourth shot area S₄. The pair of head units 60is in a stationary state also on this operation.

As is described so far, with liquid crystal exposure apparatus 10according to the embodiment, since mask encoder system 48 for obtainingposition information of mask M within the XY plane and substrate encodersystem 50 for obtaining position information of substrate P within theXY plane (each refer to FIG. 1) each have a short optical path length ofthe measurement beams irradiated on the corresponding scales, influenceof air fluctuation can be reduced compared to, for example, aconventional interferometer system. Accordingly, positioning accuracy ofmask M and substrate P is improved. Also, since the influence of airfluctuation is small, partial air-conditioning equipment that becomesnecessary when using a conventional interferometer system can beomitted, which allows cost reduction.

Furthermore, in the case of using an interferometer system, while alarge and heavy bar mirror had to be provided at mask stage device 14and substrate stage device 20, in mask encoder system 48 and substrateencoder system 50 according to the embodiment, the bar mirror referredto above will not be required, which allows systems including maskholder 40 (e.g. mask stage device) and systems including substrateholder 34 (e.g. substrate stage device) to be made smaller and lighter,and to also have a better weight balance, which in turn improvesposition controllability of mask M and substrate P. Also, places to beadjusted is fewer when compared to the case of using the interferometersystem, which allows the cost of mask stage device 14 and substratestage device 20 to be reduced, and also improves maintainability. Also,adjustment at the time of assembly becomes easier (or will not berequired).

Also, since substrate encoder system 50 according to the embodiment hasa structure of obtaining the Y position information of substrate P bymoving the pair of head units 60 in the Y-axis direction on movingsubstrate P in the Y-axis direction (e.g. stepping operation), there isno need to arrange a scale extending in the Y-axis direction on thesubstrate stage device 20 side, or to increase the width in the Y-axisdirection of the scale extending in the X-axis direction (or to arrangea plurality of heads in the Y-axis direction on the apparatus mainsection 18 side). Accordingly, the structure of the substrate positionmeasurement system can be simplified, which allows cost reduction.

Also, since mask encoder system 48 according to the embodiment has astructure of obtaining the position information of mask holder 40 withinthe XY plane while appropriately switching the output of an adjacentpair of encoder heads (X head 49 x, Y head 49 y) depending on the Xposition of mask holder 40, position information of mask holder 40 canbe obtained without the information being cut off even if the pluralityof scales 46 is arranged in the X-axis direction at a predeterminedspacing (arranged separate from one another). Accordingly, there is noneed to prepare a scale having a length about the same as the movementstrokes of mask holder 40 (a length about three times the length ofscale 46 in the embodiment), which allows the cost to be reduced, and isespecially suitable for liquid crystal exposure apparatus 10 that uses alarge mask M as in the embodiment. Similarly, with substrate encodersystem 50 according to the embodiment, since the plurality of scales 52is arranged in the X-axis direction and the plurality of scales 56 isarranged in the Y-axis direction each by a predetermined spacing, thereis no need to prepare a scale having a length about the same as themovement strokes of substrate P, which is suitable for liquid crystalexposure apparatus 10 that uses a large substrate P.

Note that in the first embodiment described above, while the case hasbeen described where the pair of head units 60 each has four heads (apair of X heads 66 x and a pair of Y heads 66 y) for measuring theposition of substrate holder 34 and a total of eight heads for measuringthe position of the substrate holder is provided, the number of headsfor measuring the position of the substrate holder may be less thaneight. Hereinafter, this kind of embodiment will be described.

Second Embodiment

Next, a second embodiment will be described, based on FIGS. 17 to 20C.Since the structure of the liquid crystal exposure apparatus accordingto the second embodiment is the same as the first embodiment previouslydescribed except for the structure of a part of substrate encoder system50, only the different points will be described below, and for elementshaving the same structure and function as the first embodiment will havethe same reference code as the first embodiment and the descriptionthereabout will be omitted.

FIG. 17 shows substrate holder 34 and the pair of head units 60 ofsubstrate encoder system 50 according to the second embodiment in aplanar view, along with projection optical system 16. In FIG. 17, tomake the description comprehensive, illustration of encoder base 54 andthe like is omitted. Also, in FIG. 17, along with head unit 60 (Y slidetable 62) illustrated in a dotted line, illustration of X head 64 x andY head 64 y provided on the upper surface of Y slide table 62 is alsoomitted.

With the liquid crystal exposure apparatus according to the secondembodiment, as is shown in FIG. 17, in each of the areas on both the +Yside and the −Y side of the substrate mounting area of substrate holder34, for example, five encoder scales 152 (hereinafter simply referred toas scales 152) are arranged at a predetermined spacing in the X-axisdirection so that the grating areas are arranged separately in theX-axis direction. With the five scales 152 arranged on the +Y side ofthe substrate mounting area and the five scales 152 arranged on the −Yside, while the spacing between adjacent scales 152 (grating area) isthe same, the arrangement position of the five scales 152 on the −Y sideis, as a whole, arranged shifted to the +X side by a predetermineddistance D (a distance slightly larger than the spacing between adjacentscales 152 (grating area)) with respect to the five scales 152 on the +Yside. This is to prevent a state from occurring in which two or moreheads of the total of four heads; two X heads 66 x and two Y heads 66 yto be described later on that measure position information of substrateholder 34, do not face any of the scales (that is, to avoid anon-measurement period in which the measurement beam moves off of thescale from overlapping among the four heads).

Each scale 152 consists of a rectangular plate-shaped (strip-shaped)member in a planar view extending in the X-axis direction, made of, forexample, quartz glass. On the upper surface of each scale 152, areflective two-dimensional diffraction grating (two-dimensional grating)RG is formed, having a predetermined pitch (e.g. 1 μm) whose periodicdirection is in the X-axis direction and the Y-axis direction. In thedescription below, the grating area described earlier will also besimply called two-dimensional grating RG. Note that in FIG. 17, forconvenience of illustration, the spacing (pitch) between the grid linesof the two-dimensional grating RG is shown much wider than the actualspacing. The same also applies to other drawings that will be describedbelow. In the description below, the five scales arranged in the area onthe +Y side of substrate holder 34 is to be referred to as a firstgrating group, and the five scales arranged in the area on the −Y sideof substrate holder 34 is to be referred to as a second grating group.

To the lower surface (surface on the −Z side) of Y slide table 62 of oneof the head units 60 positioned on the +Y side, X head 66 x and Y head66 y are fixed apart by a predetermined spacing (a distance larger thanthe spacing between adjacent scales 152) in the X-axis direction, in astate each facing scale 152. Similarly, to the lower surface (surface onthe −Z side) of Y slide table 62 of the other head unit 60 positioned onthe −Y side, Y head 66 y and X head 66 x are fixed apart by apredetermined spacing in the X-axis direction, in a state each facingscale 152. That is, X head 66 x and Y head 66 y facing the first gratinggroup and X head 66 x and Y head 66 y facing the second grating groupeach irradiates scale 152 with a measurement beam at a spacing largerthan the spacing between adjacent grating areas of scale 152. In thedescription below, for convenience of explanation, X head 66 x and Yhead 66 y that one of the head units 60 has will be referred to as head66 a and head 66 b, and Y head 66 y and X head 66 x that the other headunit 60 has will be referred to as head 66 c and head 66 d,respectively.

In this case, head 66 a and head 66 c are arranged at the same Xposition (on the same straight line parallel to the Y-axis direction),and head 66 b and head 66 d are arranged at the same X position (on thesame straight line parallel to the Y-axis direction) different from theX position of head 66 a and head 66 c. Heads 66 a, 66 d and thetwo-dimensional gratings RG that face each head structure a pair of Xlinear encoders, and heads 66 b, 66 c and the two-dimensional gratingsRG that face each head structure a pair of Y linear encoders.

With the liquid crystal exposure apparatus according to the secondembodiment, the structure of other parts including the remaining part ofhead unit 60 is similar to liquid crystal exposure apparatus 10according to the first embodiment described earlier, except for thedrive control (position control) of substrate holder 34 using thesubstrate encoder system by main controller 90.

With the liquid crystal exposure apparatus according to the secondembodiment, position measurement of substrate holder 34 can be performedby heads 66 a to 66 d of the pair of head units 60, that is, by the pairof X linear encoders and the pair of Y linear encoders, between a firstposition where the pair of head units 60 face the +X edge of substrateholder 34 as is shown in FIG. 18A, and a second position where the pairof head units 60 face the −X edge of substrate holder 34 as is shown inFIG. 18B, within a range where substrate holder 34 moves in the X-axisdirection. FIG. 18A shows a state in which only head 66 b faces none ofthe scales 152, and FIG. 18B shows a state in which only head 66 c facesnone of the scales 152.

In the process of substrate holder 34 moving in the X-axis directionbetween the first position shown in FIG. 18A and the second positionshown in FIG. 18B, positional relation between the pair of head units 60and scales changes between five states; a first to fourth state shownrespectively in FIGS. 19A to 19D and a fifth state in which four heads66 a to 66 d all face the two-dimensional grating RG of either one ofthe scales 152 (that is, all four heads 66 a to 66 d irradiatetwo-dimensional grating RG with the measurement beams). In thedescription below, instead of saying that the head faces two-dimensionalgrating RG of scale 152, or two-dimensional grating RG of scale 152 isirradiated with the measurement beam, the expression, the head faces thescale, will simply be used.

Here, for convenience of explanation, six scales 152 will be picked, andto identify each scale, reference codes a to f will be used and thescales will be described as scales 152 a to 152 f (refer to FIG. 19A).

The first state in FIG. 19A shows a state in which head 66 a faces scale152 b, heads 66 c and 66 d face scale 152 c, and only head 66 b facesneither of the scales, and the second state in FIG. 19B shows a state inwhich substrate holder 34 moves by a predetermined distance in the +Xdirection from the state shown in FIG. 19A so that heads 66 a and 66 bface scale 152 b, head 66 d faces scale 152 e, and head 66 c no longerfaces any of the scales. In the process of the state changing from thestate shown in FIG. 19A to the state shown in FIG. 19B, the process goesthrough the fifth state in which heads 66 a and 66 b face scale 152 band heads 66 c and 66 d face scales 152 e.

The third state in FIG. 19C shows a state in which substrate holder 34moves by a predetermined distance in the +X direction from the stateshown in FIG. 19B so that only head 66 a no longer faces any of thescales. In the process of the state changing from the state shown inFIG. 19B to the state shown in FIG. 19C, the process goes through thefifth state in which heads 66 a and 66 b face scale 152 b, head 66 cfaces scale 152 d, and head 66 d faces scales 152 e.

The fourth state in FIG. 19D shows a state in which substrate holder 34moves by a predetermined distance in the +X direction from the stateshown in FIG. 19C so that only head 66 d no longer faces any of thescales. In the process of the state changing from the state shown inFIG. 19C to the state shown in FIG. 19D, the process goes through thefifth state in which head 66 a faces scale 152 a, head 66 b faces scale152 b, head 66 c faces scale 152 d, and head 66 d faces scales 152 e.

When substrate holder 34 moves by a predetermined distance in the +Xdirection from the state shown in FIG. 19D, after the process goesthrough the fifth state in which head 66 a faces scale 152 a, head 66 bfaces scale 152 b, and heads 66 c and 66 d face scale 152 d, then, thestate moves into the first state in which head 66 a faces scale 152 a,heads 66 c and 66 d face scale 152 d, and only head 66 b faces neitherof the scales.

While the description so far is about the change of state (positionalrelation) between each of the three scales 152 of the five scales 152arranged on both the +Y side and the −Y side of substrate holder 34 andthe pair of head units 60, also between 10 scales 152 and the pair ofhead units 60, regarding each of the adjacent three scales 152 of thefive scales 152 arranged on both the +Y side and the −Y side ofsubstrate holder 34, the positional relation with the pair of head units60 changes in a similar order as is described above.

As is described so far, in the second embodiment, even if substrateholder 34 is moved in the X-axis direction, at least three out of thetotal of four heads; the two X heads 66 x, namely heads 66 a and 66 d,and two Y heads 66 y, namely heads 66 b and 66 c, constantly face anyone of scales 152 (two-dimensional grating RG). Moreover, even ifsubstrate holder 34 is moved in the Y-axis direction, since the pair ofY slide tables 62 is moved so that for all four heads, the measurementbeams in the Y-axis direction do not move off of scales 152(two-dimensional grating RG), at least three of the four headsconstantly face any one of scales 152. Accordingly, main controller 90can control position information of substrate holder 34 in the X-axisdirection, the Y-axis direction, and the θz direction, constantly, usingthree heads of heads 66 a to 66 d. This point will be described furtherbelow.

When measurement values of X head 66 x and Y head 66 y are to be CX andCY, measurement values C_(X) and C_(Y) can each be expressed by thefollowing formulas, (1a) and (1b).C _(X)=(p _(i) −X)cos θz+(q _(i) −Y)sin θz  (1a)C _(Y)=−(p _(i) −X)sin θz+(q _(i) −Y)cos θz  (1b)

Here, X, Y, and θx show the position of substrate holder 34 in theX-axis direction, the Y-axis direction, and the θz direction,respectively. Also, p_(i) and q_(i) are the X position (X coordinatevalue) and the Y position (Y coordinate value) of each of the heads 66 ato 66 d. In the embodiment, the X coordinate values p_(i) and the Ycoordinate values q_(i) (i=1, 2, 3, 4) of each of the heads 66 a, 66 b,66 c, and 66 d can be calculated easily from the position information inthe X-axis direction and the Y-axis direction (position of the center ofY slide table 62 in the X-axis direction and the Y-axis direction) ofeach of the pair of head units 60 (refer to FIG. 1) calculated from theoutput of the four X linear encoders 96 x and the four Y linear encoders96 y, based on a known relation of each head with respect to the centerof Y slide table 62.

Accordingly, when substrate holder 34 and the pair of head units 60 havea positional relation as is shown in FIG. 18A and the position ofsubstrate holder 34 within the XY plane in directions of three degreesof freedom is (X, Y, θz), then measurement values of the three heads 66a, 66 c, and 66 d can theoretically be expressed by the followingformulas, (2a) to (2c) (also called an affine transformation relation).C _(i)=(p ₁ −X)cos θz+(q ₁ −Y)sin θz  (2a)C ₃=−(p ₃ −X)sin θz+(q ₃ −Y)cos θz  (2b)C ₄=(p ₄ −X)cos θz+(q ₄ −Y)sin θz  (2c)

In a reference state where substrate holder 34 is at a coordinate origin(X, Y, θz)=(0, 0, 0), by simultaneous equations (2a) to (2c), C₁=p₁,C₃=q₃, and C₄=p₄. The reference state, for example, is a state in whichthe center of substrate holder 34 (almost coincides with the center ofsubstrate P) coincides with the center of the projection area byprojection optical system 16 and the θz rotation is zero. Accordingly,in the reference state, the Y position of substrate holder 34 can alsobe measured by head 66 b, and measurement value C₂ by head 66 b,according to formula (1b), is C₂=q₂.

Accordingly, when the measurement values of the three heads 66 a, 66 c,and 66 d are to be initially set to p₁, q₃, and p₄ in the referencestate, hereinafter, the three heads 66 a, 66 c, and 66 d are to presenttheoretical values given by the formulas (2a) to (2c) with respect todisplacements (X, Y, θz) of substrate holder 34.

Note that in the reference state, instead of one of the heads 66 a, 66c, and 66 d, such as for example, 66 c, measurement value C₂ of head 66b may be initially set as q₂.

In this case, hereinafter, the three heads 66 a, 66 b, and 66 d are topresent theoretical values given by the formulas (2a), (2c), and (2d)with respect to displacements (X, Y, θz) of substrate holder 34.C ₁=(p ₁ −X)cos θz+(q ₁ −Y)sin θz  (2a)C ₄=(p ₄ −X)cos θz+(q ₄ −Y)sin θz  (2c)C ₂=−(p ₂ −X)sin θz+(q ₂ −Y)cos θz  (2d)

In simultaneous equations (2a) to (2c) and simultaneous equations (2a),(2c), and (2d), three formulas are given with respect to three variables(X, Y, θz). Therefore, conversely, if dependent variables C₁, C₃, and C₄in simultaneous equations (2a) to (2c), or dependent variables C₁, C₄,and C₂ in simultaneous equations (2a), (2c), and (2d) are given,variables X, Y, and θz can be obtained. Here, the equations can besolved easily when an approximate sin θz≈θz is applied, or when a higherapproximate is applied. Accordingly, positions (X, Y, θz) of wafer stageWST can be calculated from measurement values C₁, C₃, and C₄ (or C₁, C₂,and C₄) of heads 66 a, 66 c, and 66 d (or heads 66 a, 66 b, and 66 d).

Next, a linkage process, namely, initial setting of measurement values,at the time when switching heads of the substrate encoder system thatmeasures position information of substrate holder 34 performed in theliquid crystal exposure apparatus according to the second embodiment,will be described centering on the operation of main controller 90.

In the second embodiment, three encoders (X heads and Y heads) areconstantly measuring the position information of substrate holder 34 asis previously described in an effective stroke range of substrate holder34, and on performing the switching process of the encoders (X head or Yhead), for example, as is shown in FIG. 20B, each of the four heads 66 ato 66 d face any of the scales 152 and moves into a state (the fifthstate described earlier) so that the position of substrate holder 34 canbe measured. FIG. 20B shows an example of the fifth state that appearsduring the change of state from the state shown in FIG. 20A in which theposition of substrate holder 34 is measured with heads 66 a, 66 b, and66 d and then substrate holder 34 is moved in the +X direction to thestate shown in FIG. 20C in which the position of substrate holder 34 ismeasured with heads 66 b, 66 c, and 66 d. That is, FIG. 20B shows astate in which the three heads used for measuring position informationof substrate holder 34 are being switched, from heads 66 a, 66 b, and 66d to heads 66 b, 66 c, and 66 d.

At the moment when the switching process (linkage) of heads (encoders)used for position control (measurement of position information) ofsubstrate holder 34 within the XY plane, heads 66 a, 66 b, 66 c, and 66d are facing scales 152 b, 152 b, 152 d, and 152 e, respectively, as isshown in FIG. 20B. When taking a look at FIGS. 20A to 20C, it may appearthat head 66 a is about to be switched to head 66 c in FIG. 20B,however, as it is obvious from the point that the measurement directionis different in head 66 a and head 66 c, it is meaningless to give themeasurement value (count value) of head 66 a without any changes to head66 c as an initial value of the measurement value at the timing whenlinkage is performed.

Therefore, in the embodiment, main controller 90 is to perform switchingfrom the measurement of position information (and position control) ofsubstrate holder 34 using the three heads 66 a, 66 b, and 66 d to themeasurement of position information (and position control) of substrateholder 34 using the three heads 66 b, 66 c, and 66 d. That is, thismethod is different from the concept of a normal encoder linkage anddoes not link one head to another head, but is a method of linking acombination of three heads (encoders) to another combination of threeheads (encoders).

Main controller 90, first of all, solves simultaneous equations (2a),(2c), and (2d) based on measurement values C₁, C₄, and C₂ of heads 66 a,66 d, and 66 b, and calculates position information (X, Y, θz) of thesubstrate holder within the XY plane.

Next, main controller 90 substitutes X and θz calculated above into thefollowing affine transformation formula (formula (3)), and obtains theinitial value (the value that should be measured by head 66 c) of themeasurement value of head 66 c.C ₃=−(p ₃ −X)sin θz+(q ₃ −Y)cos θz  (3)

In formula (3) above, p₃ is the X coordinate value and q₃ is the Ycoordinate value of head 66 c. In the embodiment, as is describedearlier, for X coordinate value p₃ and Y coordinate value q₃, the valuesare used that are calculated from the position of the center of Y slidetable 62 in the X-axis direction and the Y-axis direction of each of thepair of head units 60 calculated from the output of the four X linearencoders 96 x and the four Y linear encoders 96 y, based on the knownpositional relation of head 66 c with respect to the center of Y slidetable 62.

By giving initial value C₃ described above as the initial value of head66 c, linkage is to be completed without contradictions whilemaintaining the positions (X, Y, θz) of substrate holder 34 indirections of three degrees of freedom. Thereinafter, the positions (X,Y, θz) of wafer stage WST is calculated by solving the followingsimultaneous equations (2b) to (2d), using the measurement values C₂,C₃, and C₄ of heads 66 b, 66 c, and 66 d which are used after theswitching.C ₃=−(p ₃ −X)sin θz+(q ₃ −Y)cos θz  (2b)C ₄=(p ₄ −X)cos θz+(q ₄ −Y)sin θz  (2c)C ₂=−(p ₂ −X)sin θz+(q ₂ −Y)cos θz  (2d)

Note that while the case has been described above when the switching isfrom three heads to another three heads including one head differentfrom the three heads, it was described in this way because the values tobe measured using the another heads after switching is calculated basedon the principle of affine transformation, using the positions (X, Y,θz) of substrate holder 34 obtained from the measurement values of thethree heads used before switching, and the calculated values are set asinitial values of the another heads used after switching. However, whenfocusing only on the two heads serving as direct targets of switchingand linkage process, without referring to the procedure of calculationand the like of the values to be measured using the another heads usedafter switching, it may also be said that one head of the three headsused before switching is switched to a different head. In any case, theswitching of the heads is performed in a state where the head used formeasurement of position information and position control of thesubstrate holder before switching and the head used after switching bothsimultaneously face any of the scales 152.

Note that while the description above is an example of switching ofheads 66 a to 66 d, in switching from any three heads to another threeheads, or switching from one of the heads to another head, switching ofheads is performed in a procedure similarly to the procedure describedabove.

The liquid crystal exposure apparatus according to the second embodimentdescribed so far has a working effect equivalent to the liquid crystalexposure apparatus according to the first embodiment described earlier.Adding to this, with the liquid crystal exposure apparatus according tothe second embodiment, while substrate holder 34 is moved, positioninformation (including θz rotation) of substrate holder 34 within the XYplane is measured by three heads (encoders) including at least one eachof X head 66 x (X linear encoder) and Y head 66 y (Y linear encoder) ofsubstrate encoder system 50. Then, by main controller 90, the head(encoder) used for measuring position information of substrate holder 34within the XY plane is switched from one of the heads (encoders) of thethree heads used for position measurement and position control ofsubstrate holder 34 before switching to another head (encoder), so thatthe position of substrate holder 34 within the XY plane is maintainedbefore and after the switching. Therefore, the position of substrateholder 34 within the XY plane is maintained before and after theswitching and an accurate linkage becomes possible, even thoughswitching of the encoders used for controlling the position of substrateholder 34 has been performed. Accordingly, substrate holder 34(substrate P) can be moved along the XY plane accurately along apredetermined moving route while switching and linkage (linkage processof measurement values) of the heads are performed among a plurality ofheads (encoders).

Also, with the liquid crystal exposure apparatus according to the secondembodiment, for example, during exposure of the substrate, substrateholder 34 is moved within the XY plane by main controller 90, based onmeasurement results of position information of substrate holder 34 andposition information ((X, Y) coordinate values) within the XY plane ofthe three heads used for measuring the position information. In thiscase, main controller 90 moves substrate holder 34 within the XY planewhile calculating the position information of substrate holder 34 withinthe XY plane using the affine transformation relation. This allows themovement of substrate holder 34 (substrate P) to be controlled with goodaccuracy while switching the heads (encoders) used for control of themovement of substrate holder 34 using the encoder system having each ofa plurality of Y heads 66 y or a plurality of X heads 66 x.

Note that in the second embodiment described above, while the correctioninformation (initial value of the another head previously described) forcontrolling the movement of the substrate holder using the head(corresponding to the another head described above) whose measurementbeam moves off from one of the adjacent pair of scales and moves toirradiate the other scale was acquired, based on the positioninformation measured by the three heads facing at least one scale 152,this correction information should be acquired by the time one of thethree heads facing at least one scale 152 moves off of two-dimensionalgrating RG, after the measurement beam of the another head is moved toirradiate the other scale. Also, in the case of performing positionmeasurement or position control of the substrate holder by switching thethree heads facing at least one scale 152 to three different headsincluding the another head described above, this switching should beperformed by the time one of the three heads facing at least one scale152 moves off of two-dimensional grating RG, after the correctioninformation described above has been acquired. Note that acquiring thecorrection information and the switching may substantially be performedat the same time.

Note that in the second embodiment described above, each of the fivescales 152 of the first grating group and the second grating group isarranged on substrate holder 34 so that the area that has notwo-dimensional grating RG of the first grating group (non-grating area)does not overlap the area that has no two-dimensional grating RG of thesecond grating group (non-grating area) in the X-axis direction (firstdirection), or in other words, so that the non-measurement period inwhich the measurement beam moves off of two-dimensional grating RG doesnot overlap in the four heads. In this case, heads 66 a and 66 b thathead unit 60 on the +Y side has, are arranged at a spacing wider thanthe width of the area that has no two-dimensional grating RG of thefirst group in the X-axis direction, and heads 66 c and 66 d that headunit 60 on the −Y side has, are arranged at a spacing wider than thewidth of the area that has no two-dimensional grating RG of the secondgroup in the X-axis direction. However, the combination of the gratingsection including the plurality of two-dimensional gratings and theplurality of heads that can face the grating section is not limited tothis. The point is, spacing between heads 66 a and 66 b and spacingbetween heads 66 c and 66 d, position, position and length of thegrating section of the first and second grating groups, spacing betweenthe grating sections, and their position should be set, so that the(non-measurable) non-measurement period in which the measurement beammoves off of two-dimensional grating RG does not overlap in the fourheads 66 a, 66 b, 66 c, and 66 d during the movement of the movable bodyin the X-axis direction. For example, even if the position and the widthof the non-grating area in the X-axis direction is the same in the firstgrating group and the second grating group, two heads facing at leastone scale 152 (two-dimensional grating RG) of the first grating groupand two heads facing at least one scale 152 (two-dimensional grating RG)of the second grating group may be arranged shifted only by a distancewider than the width of the non-grating area in the X-axis direction. Inthis case, the spacing between the head arranged on the +X side of thetwo heads facing the first grating group and the head arranged on the −Xside of the two heads facing the second grating group may be set widerthan the width of the non-grating area, or the two heads facing thefirst grating and the two heads facing the second grating may bearranged alternately in the X-axis direction with the spacing betweenadjacent pair of heads may be set wider than the width of thenon-grating area.

Also, in the second embodiment described above, while the case has beendescribed in which the first grating group is arranged in an area on the+Y side of substrate holder 34, and the second grating group is arrangedin an area on the −Y side of substrate holder 34, instead of one of thefirst grating group and the second grating group, such as the firstgrating group, a single scale member on which a two-dimensional gratingextending in the X-axis direction is formed may be used. In this case,one head may be made to constantly face the single scale member. In thiscase, a structure may be employed in which three heads may be providedto face the second grating group, and by making the spacing (spacingbetween irradiation positions of the measurement beams) in the X-axisdirection of the three heads wider than the spacing betweentwo-dimensional grating RG on adjacent scales 152, at least two of thethree heads facing the second grating group can face at least onetwo-dimensional grating RG of the second grating group regardless of theposition of substrate holder 34 in the X-axis direction. Or, a structuremay be employed in which at least two heads constantly face the singlescale member described above regardless of the position of substrateholder 34 in the X-axis direction, together with at least two headsfacing at least one two-dimensional grating RG of the second gratinggroup. In this case, each of the measurement beams of the at least twoheads moves off of one of the plurality of scales 152 (two-dimensionalgrating RG) during the movement of substrate holder 34 in the X-axisdirection, and is moved to irradiate another scale 152 (two-dimensionalgrating RG) adjacent to the one scale 152 (two-dimensional grating RG).However, by making the spacing between the at least two heads in theX-axis direction wider than the spacing of two-dimensional grating RG ofadjacent scales 152, the non-measurement period does not overlap in theat least two heads, that is, the measurement beam of at least one headconstantly irradiates scale 152. In these structures, at least threeheads constantly face at least one scale 152, allowing positioninformation in directions of three degrees of freedom to be measured.

Note that the number of scales, spacing between adjacent scales and thelike may be different in the first grating group and the second gratinggroup. In this case, in at least two heads facing the first gratinggroup and at least two heads facing the second grating group, spacingbetween the heads (measurement beams), position and the like may bedifferent.

Note that in the second embodiment described above, the position ofheads 66 a to 66 d in the X-axis direction and the Y-axis direction arecalculated from the position of the center of Y slide table 62 in theX-axis direction and the Y-axis direction of each of the pair of headunits 60 calculated from the output of the four X linear encoders 96 xand the four Y linear encoders 96 y, based on the known positionalrelation of each head with respect to the center of Y slide table 62.That is, the encoder system was to be used for measuring the position ofheads 66 a to 66 d in the X-axis direction and the Y-axis direction.However, the embodiment is not limited to this, and the encoder systemand the like may be used to measure position information only in theY-axis direction of heads 66 a to 66 d, since heads 66 a to 66 d (thepair of head units 60) can be moved only in the Y-axis direction. Thatis, in the second embodiment described above, the four X linear encoders96 x do not necessarily have to be provided. In this case, for heads 66a to 66 d, on applying formulas (2a) to (2d) described earlier, designvalues (fixed values) are used for p₁ to p₄ (X position), and for q₁ toq₄ (Y position), values calculated from the output of the four linearencoders 96 y are used. Note that in the case the affine transformationrelation is not used, on measuring position information in the Y-axisdirection of substrate holder 34 by heads 66 b and 66 c, measurementinformation of the four linear encoders 96 y is used, and on measuringposition information in the X-axis direction of substrate holder 34 byheads 66 a and 66 d, measurement information of the four Y linearencoders 96 y do not have to be used.

Note that in the second embodiment described above, while the pluralityof scales 152 having a single two-dimensional grating RG (grating area)formed on each scale was used, the present invention is not limited tothis, and at least one of the first grating group or the second gratinggroup may include a scale 152 that has two or more grating areas formedapart in the X-axis direction.

Note that in the second embodiment described above, while the case hasbeen described in which to measure and control the positions (X, Y, θz)of substrate holder 34 constantly by three heads, the first gratinggroup and the second grating group including five scales 152 each havingthe same structure are arranged shifted by a predetermined distance inthe X-axis direction, the embodiment is not limited to this, and one ofthe head units 60 and the other of the head units 60 may have heads (66x, 66 y) used for measurement of substrate holder 34 arrangeddifferently in the X-axis direction, without the first grating group andthe second grating group being shifted in the X-axis direction (arrangedthe line of scales 152 almost completely facing each other). Also inthis case, the positions (X, Y, θz) of substrate holder 34 canconstantly be measured and controlled by the three heads.

Note that in the second embodiment described above, while the case ofusing a total of four heads, heads 66 a and 66 b and heads 66 c and 66 dhas been described, the embodiment is not limited to this, and five ormore heads may also be used. That is, to one of the two heads eachfacing the first grating group and the second grating group, at leastone of redundant head may be added. This structure will be described ina third embodiment below.

Third Embodiment

Next, a third embodiment will be described, based on FIG. 21. Since thestructure of the liquid crystal exposure apparatus according to thethird embodiment is the same as the first and the second embodimentspreviously described except for the structure of a part of substrateencoder system 50, only the different points will be described below,and for elements having the same structure and function as the first andthe second embodiments will have the same reference code as the firstand the second embodiments, and the description thereabout will beomitted.

FIG. 21 shows substrate holder 34 and the pair of head units 60 ofsubstrate encoder system 50 according to the third embodiment in aplanar view, along with projection optical system 16. In FIG. 21, tomake the description comprehensive, illustration of encoder base 54 andthe like is omitted. Also, in FIG. 21, along with head unit 60 (Y slidetable 62) illustrated in a dotted line, illustration of X head 64 x andY head 64 y provided on the upper surface of Y slide table 62 is alsoomitted.

With the liquid crystal exposure apparatus according to the thirdembodiment, as is shown in FIG. 21, in each of the areas on the +Y sideand the −Y side of substrate holder 34 with the substrate mounting areain between, for example, five scales 152 are arranged at a predeterminedspacing in the X-axis direction. With the five scales 152 arranged onthe +Y side of the substrate mounting area and the five scales 152arranged on the −Y side, the spacing between adjacent scales 152 is thesame, and the five scales 152 on the +Y side of the substrate mountingarea and the five scales 152 on the −Y side are arranged at the same Xposition, facing each other. Accordingly, the position of the spacingbetween adjacent scales is located on almost the same straight line inthe Y-axis direction that has a predetermined width.

To the lower surface (surface on the −Z side) of Y slide table 62 of oneof the head units 60 positioned on the +Y side, a total of three heads,Y head 66 y, X head 66 x, and Y head 66 y are fixed apart by apredetermined spacing (a distance larger than the spacing betweenadjacent scales 152) in the X-axis direction from the −X side, in astate each facing scale 152. To the lower surface (surface on the −Zside) of Y slide table 62 of the other head unit 60 positioned on the −Yside, Y head 66 y and X head 66 x are fixed apart by a predeterminedspacing in the X-axis direction, in a state each facing scale 152. Inthe description below, for convenience of explanation, three heads thatone of the head units 60 has will be referred to as head 66 e, head 66a, and head 66 b from the −X side, and Y head 66 y and X head 66 x thatthe other head unit 60 has will be referred to as head 66 c and head 66d, respectively.

In this case, head 66 a and head 66 c are arranged at the same Xposition (on the same straight line in the Y-axis direction), and head66 b and head 66 d are arranged at the same X position (on the samestraight line in the Y-axis direction). Heads 66 a, 66 d and thetwo-dimensional gratings RG that face each head structure a pair of Xlinear encoders, and heads 66 b, 66 c, and 66 e and the two-dimensionalgratings RG that face each head structure three Y linear encoders.

With the liquid crystal exposure apparatus according to the thirdembodiment, the structure of other parts is similar to the liquidcrystal exposure apparatus according to the second embodiment describedearlier.

In the third embodiment, although the arrangement of scales 152 lined onthe +Y side and the −Y side is not shifted in the X-axis direction, aslong as the pair of head units 60 moves (or the Y position of substrateholder 4 is maintained at a position where the pair of head units 60faces the line of scale 152) in the Y-axis direction synchronously withsubstrate holder 34, three heads of heads 66 a to 66 e constantly facesscale 152 (two-dimensional grating RG) regardless of the X position ofsubstrate holder 34.

The liquid crystal exposure apparatus according to the third embodimentdescribed so far has a working effect equivalent to the liquid crystalexposure apparatus according to the second embodiment described earlier.

Note that in the third embodiment described above, the plurality ofheads for measuring position information of substrate holder 34 can alsobe regarded to include one head 66 a in addition to, e.g. heads 66 e, 66b, 66 c, and 66 d necessary for switching of the heads, whosenon-measurement period partly overlaps one head 66 c of the four heads.And, in the third embodiment, on measuring position information (X, Y,θz) of substrate holder 34, of the five heads including the four heads66 e, 66 b, 66 c, and 66 d and the one head 66 c, measurementinformation is used of at least three heads irradiating at least one ofthe plurality of grating areas (two-dimensional grating RG) with ameasurement beam.

Note that the third embodiment described above is an example of a casewhen the non-measurement period overlaps in at least two heads of aplurality of heads, for example, two heads move off of scale 152(grating area, e.g. two-dimensional grating RG) at the same time, andsimultaneously move to face an adjacent scale 152 (grating area, e.g.two-dimensional grating RG). In this case, to continue measurement evenif the measurement is cut off for the at least two heads, at least threeheads need to face the grating area (two-dimensional grating) of thegrating section. Moreover, as a premise, the measurement should not becut off for the at least three heads until one or more of the at leasttwo heads whose measurement has been cut off switches to face anadjacent grating area. That is, even if there is at least two headswhose non-measurement period overlaps, if there is at least three headsadding to the at least two heads, measurement can be continued even ifthe grating areas are arranged spaced apart.

Fourth Embodiment

Next, a fourth embodiment will be described, based on FIG. 22. While thestructure of the liquid crystal exposure apparatus according to thefourth embodiment is different from the structure of the liquid crystalexposure apparatus according to the second embodiment described earlieron the points that scales 52 lined in each of the areas on both the +Yside and the −Y side of the substrate mounting area of substrate holder34 are arranged facing each other similarly as in the third embodiment,and that one of the head units 60 positioned on the −Y side has two eachof X heads 66 x and Y heads 66 y similarly to the first embodiment, asis shown in FIG. 22, the structure of other parts is similar to theliquid crystal exposure apparatus according to the second embodiment.

To the lower surface (surface on the −Z side) of Y slide table 62 of oneof the head units 60, X head 66 x (hereinafter appropriately called head66 e) is provided arranged adjacent to Y head 66 y (head 66 c) on the −Yside, along with Y head 66 y (hereinafter appropriately called head 66f) provided arranged adjacent to X head 66 x (head 66 d) on the −Y side.

With the liquid crystal exposure apparatus according to the embodiment,in a state when the pair of head units 60 is moving in the Y-axisdirection (or when the Y position of substrate holder 34 is maintainedat a position where the pair of head units 60 face the scales 152lined), a case may occur when one of three heads 66 a, 66 c, and 66 e(to be referred to as heads of a first group) and three heads 66 b, 66d, and 66 f (to be referred to as heads of a second group) do not faceany of the scales due to substrate holder 34 moving in the X-axisdirection, and when this occurs, the other of the heads of the firstgroup and the heads of the second group face scale 152 (two-dimensionalgrating RG) without fail. That is, in the liquid crystal exposureapparatus according to the fourth embodiment, although the arrangementof scales 152 lined on the +Y side and the −Y side is not shifted in theX-axis direction, as long as the pair of head units 60 moves (or the Yposition of substrate holder 4 is maintained at a position where thepair of head units 60 faces the line of scale 152) in the Y-axisdirection, the positions (X, Y, θz) of substrate holder 34 can bemeasured regardless of the X position of substrate holder 34, by thethree heads included in at least one of the heads of the first group andthe heads of the second group.

Here, a case will be considered, for example, of restoring (re-startmeasurement of) the heads of the first group (heads 66 a, 66 c, and 66e) when the heads face scale 152 again, after heads 66 a, 66 c, and 66 eno longer face any of the scales and have become non-measurable. In thiscase, at the point before measurement is re-started by the heads of thefirst group (heads 66 a, 66 c, and 66 e), the positions (X, Y, θz) ofsubstrate holder 34 is being continuously measured and controlled by theheads of the second group (heads 66 b, 66 d, and 66 f). Therefore, maincontroller 90, as is shown in FIG. 22, at the point when the pair ofhead units 60 crosses over adjacent two scales 152 arranged on each ofthe +Y side and the −Y side and the heads of the first group and theheads of the second group face one and the other of the adjacent twoscales 152, respectively, calculates the positions (X, Y, θz) ofsubstrate holder 34 by the method described in detail in the secondembodiment based on measurement values of the heads of the second group(heads 66 b, 66 d, and 66 f), and by substituting the positions (X, Y,θz) of the substrate holder into the formula of affine transformationdescribed earlier, initial values of the heads of the first group (heads66 a, 66 c, and 66 e) are calculated and set at the same time. Thisallows the heads of the first group to be restored and to re-startmeasurement and control of the position of substrate holder 34 withthese heads easily.

With the liquid crystal exposure apparatus according to the fourthembodiment described so far, the apparatus exhibits a working effectequivalent to the liquid crystal exposure apparatus according to thesecond embodiment described earlier.

Modified Example of the Fourth Embodiment

This modified example describes a case when a head unit having anidentical structure (or a structure symmetrical in the verticaldirection of the page surface) as one of the head units 60 is used asthe other head unit 60 positioned on the +Y side, in the liquid crystalexposure apparatus according to the fourth embodiment.

In this case, similarly to the description above, eight heads aregrouped into four heads each being arranged on the same straight line inthe Y-axis direction; heads of a first group, and heads of a secondgroup.

A case will be considered of restoring the heads of a first group andre-starting measurement with these heads when the heads face scale 152again, after the heads of the first group no longer face any of thescales and can no longer perform measurement.

In this case, at the point before measurement is re-started by the headsof the first group, the positions (X, Y, θz) of substrate holder 34 arebeing continuously measured and controlled by three heads of the headsof the second group. Therefore, main controller 90, as is describedearlier, at the point when the pair of head units 60 crosses overadjacent two scales 152 arranged on each of the +Y side and the −Y sideand the heads of the first group and the heads of the second group faceone and the other of the adjacent two scales 152, respectively,calculates initial values of each of the heads of the first group,however, in this case, the main controller cannot calculate the initialvalues of all four heads of the first group at the same time. This isbecause if the heads to be restored for measurement were three (thenumber of X heads and Y heads added), when the initial values of themeasurement values of the three heads are set in the procedure describedearlier, by solving the simultaneous equations described earlier usingthe initial values as measurement values C₁, C₂, C₃ and the like, thepositions (X, Y, θz) of the substrate holder is uniquely decided, whichcauses no problems in particular. However, simultaneous equations usingthe affine transformation relation that can uniquely decide thepositions (X, Y, θz) of the substrate holder using measurement values offour heads cannot be conceived.

Therefore, in the modified example, the first group to be restored is tobe grouped into two groups, each having three heads including differentheads and the initial values are calculated and set simultaneously forthe three heads for each group in the method described earlier. Afterthe initial values have been set, the measurement values of either ofthe groups may be used for position control of substrate holder 34.Position measurement of substrate holder 34 by the heads of the groupnot used for position control may be executed in parallel with positioncontrol of substrate holder 34. Note that the initial values of eachhead of the first group to be restored can be sequentially calculatedindividually, by the method described earlier.

Note that the structures described so far in the first to fourthembodiments can be changed as appropriate. For example, in mask encodersystem 48 and substrate encoder system 50 of the first embodiment, thearrangement of encoder heads and scales may be reversed. That is, forexample, X linear encoder 92 x and Y linear encoder 92 y for obtainingposition information of mask holder 40 may be structured so that encoderheads are attached to mask holder 40 and scales are attached to encoderbase 43. Also, X linear encoder 94 x and Y linear encoder 94 y forobtaining position information of substrate holder 34 may have encoderheads attached to substrate holder 34 and scales attached to Y slidetable 62. In this case, the encoder heads attached to substrate holder34 may be arranged, for example, along the X-axis direction in aplurality of numbers, and are preferably structured switchable with oneanother. Also, the encoder heads provided at substrate holder 34 may bemade movable and sensors to measure position information of the encoderheads may be provided, and the scales may be provided at encoder base43. In this case, the scales provided at encoder base 43 are fixed.Similarly, X linear encoder 96 x and Y linear encoder 96 y for obtainingposition information of Y slide table 62 may have scales attached to Yslide table 62 and encoder heads attached to encoder base 54 (apparatusmain section 18). In this case, the encoder heads attached to encoderbase 54 may be arranged, for example, along the Y-axis direction in aplurality of numbers, and are preferably structured switchable with oneanother. In the case the encoder heads are fixed to substrate holder 34and encoder base 54, the scales fixed to Y slide table 62 may be used incommon.

Also, in substrate encoder system 50, while the case has been describedwhere a plurality of scales 52 are fixed extending in the X-axisdirection on the substrate stage device 20 side and a plurality ofscales 56 are fixed extending in the Y-axis direction on the apparatusmain section 18 (encoder base 54) side, the substrate encoder system isnot limited to this, and a plurality of scales extending in the Y-axisdirection may be fixed on the substrate stage device 20 side and aplurality of scales extending in the X-axis direction may be fixed onthe apparatus main section 18 side. In this case, head unit 60 is movedin the X-axis direction while substrate holder 34 is being moved inexposure operation and the like of substrate P.

Also, while the case has been described in which in mask encoder system48, for example, threes scales 46 are arranged separate in the X-axisdirection, and in substrate encoder system 50, for example, two scales52 are arranged separate in the Y-axis direction and five scales 56 arearranged separate in the X-axis direction, the number of scales is notlimited to this, and may be appropriately changed, for example,according to the size of mask M and substrate P, or movement strokes.Also, the plurality of scales may not necessarily have to be arrangedseparate, and for example, a longer single scale (in the case of theembodiment above, for example, a scale about three times the length ofscale 46, a scale about two times the length of scale 52, and a scaleabout five times the length of scale 56) may be used. Also, a pluralityof scales having different lengths may be used, and the number of scalesstructuring the grating section does not matter, as long as each of thegrating sections includes a plurality of grating areas arranged side byside in the X-axis direction or the Y-axis direction.

Also, although the structure was employed in which Y slide table 62 andbelt driver 68 are provided at the lower surface (refer to FIG. 4) ofupper mount section 18 a of apparatus main section 18, Y slide table 62and belt driver 68 may be provided at lower mount section 18 b or middlemount section 18 c.

Also, in the first embodiment described above, while the case has beendescribed where X scales and Y scales are formed independently on thesurface of each of the scales 46, 52, and 56, the embodiment is notlimited to this, and a scale having a two-dimensional grating formed maybe used, similarly to the second or fourth embodiments describedearlier. In this case, an XY two-dimensional head can be used as theencoder head. Also, in scale 52 formed on substrate holder 34, while Xscale 53 x and Y scale 53 y are formed having the same length in theX-axis direction, these lengths may be made mutually different. Also, Xscale 53 x and Y scale 53 y may be arranged relatively shifted in theX-axis direction. Also, while the case of using a diffractioninterference encoder system has been described, the encoder is notlimited to this, and other encoders such as the so-called pick-up systemor a magnetic system may also be used, and the so-called scan encoderwhose details are disclosed in, for example, U.S. Pat. No. 6,639,686 mayalso be used. Also, position information of Y slide table 62 may beobtained by a measurement system other than the encoder system (e.g. anoptical interferometer system).

Note that in the second to fourth embodiments and the modified example(hereinafter shortly referred to as the fourth embodiment) describedabove, while the case has been described in which at least four headsare provided, in such a case, the number of scales 152 structuring thegrating section does not matter, as long as the grating section includesa plurality of grating areas arranged side by side in the firstdirection. The plurality of grating areas does not necessarily have tobe arranged on both one side and the other side in the Y-axis directionwith substrate P of substrate holder 34 in between, and may be arrangedonly on one side. However, to continuously control the positions (X, Y,θz) of substrate holder 34 at least during the exposure operation ofsubstrate P, the following conditions need to be satisfied.

That is, while a measurement beam of one head of the at least four headsmoves off of the plurality of grating areas (e.g. two-dimensionalgrating RG described earlier), along with at least the three headsremaining irradiate at least one of the plurality of grating areas withthe measurement beams, by movement of substrate holder 34 in the X-axisdirection (the first direction), the one head described above whosemeasurement beam moves off of the plurality of grating areas is switchedin the at least four heads described above. In this case, the at leastfour heads include; two heads whose positions (irradiation positions) ofthe measurement beams in the X-axis direction (the first direction) aredifferent from each other, and two heads whose positions of themeasurement beams in the Y-axis direction (the second direction) aredifferent from at least one of the two heads along with positions(irradiation positions) of the measurement beams in the X-axis direction(the first direction) being different from each other, and the two headsirradiate measurement beams in the X-axis direction at a spacing widerthan the spacing of a pair of adjacent grating areas of the plurality ofgrating areas.

Note that the grating areas (e.g. two-dimensional grating RG) arrangedside by side in the X-axis direction may be arranged in the Y-axisdirection in three or more rows. For example, in the fourth embodimentdescribed above, instead of the five scales 152 on the −Y side, astructure may be employed in which two rows of grating areas (e.g.two-dimensional gratings RG) adjacent in the Y-axis direction areprovided, consisting of 10 grating areas (e.g. two-dimensional gratingsRG) having an area which is half of each of the five scales 152 in theY-axis direction, and heads 66 e and 66 f can be made to facetwo-dimensional grating RG, at one of the rows and heads 66 c and 66 dcan be made to face two-dimensional grating RG at the other of the rows.Also, in the modified example of the fourth embodiment described above,also for the five scales 152 on the +Y side, a structure may be employedin which two rows of grating areas (e.g. two-dimensional gratings RG)adjacent in the Y-axis direction are provided, consisting of 10 gratingareas similar to the description above, and a pair of heads can be madeto face two-dimensional grating RG at one of the rows, and the remainingpair of heads can be made to face two-dimensional grating RG at theother of the rows.

Note that in the second to fourth embodiments described above, whensubstrate holder 34 moves in the X-axis direction (the first direction),it is important to set position or spacing, or position and spacing andthe like of at least one of scales and heads, so that at least among thefour heads mutually, measurement beams not being irradiated on (move offof the grating areas of) any of the two-dimensional grating RG, that is,measurement with the heads being non-measurable (non-measurementsection) does not overlap for any two heads.

Note that in the second or the fourth embodiment described above,instead of each X head 66 x measuring position information of substrateholder 34, an encoder head (XZ head) whose measurement direction is inthe X-axis direction and the Z-axis direction may be used, together withan encoder head (YZ head) whose measurement direction is in the Y-axisdirection and the Z-axis direction. As these heads, a sensor head havinga structure similar to the displacement measurement sensor headdisclosed in, for example, U.S. Pat. No. 7,561,280, can be used. In sucha case, on switching and linkage process of the heads described earlier,adding to the linkage process performed to secure continuity ofmeasurement results of the position of substrate holder 34 in directionsof three degrees of freedom (X, Y, θz) in the XY plane by performing apredetermined calculation using measurement values of three heads usedfor position control of substrate holder 34 before switching, maincontroller 90 may also perform the linkage process to secure continuityof measurement results of the position of substrate holder 34 in theremaining directions of three degrees of freedom (Z, θx, θy) by asimilar method described earlier. Specifically, taking the secondembodiment representatively as an example, main controller 90 mayacquire correction information for controlling the movement of substrateholder 34 in the remaining directions of three degrees of freedom (Z,θx, θy) using one head whose measurement beam moves off of onetwo-dimensional grating RG (grating area) and moves to irradiate anothertwo-dimensional grating RG (grating area) of the four heads 66 a, 66 b,66 c, and 66 d, based on measurement information in the Z-axis direction(a third direction) by the remaining three heads or position informationof substrate holder 34 in the remaining directions of three degrees offreedom (Z, θx, θy) measured by the remaining three heads.

Note that in the second or the fourth embodiment, while the initialvalue of another head to be switched is to be set when a measurementbeam moves off of one scale and moves to irradiate another scale, theembodiment is not limited to this, and correction information forcontrolling the substrate holder may be acquired using another head,such as correction information of the measurement values of anotherhead. In the correction information to control the movement of thesubstrate holder using another head, the initial value is naturallyincluded, but the information is not limited to this, and as long as theinformation may be used so that the another head can start themeasurement again, the information may also be an offset value from thevalues to be measured after re-starting the measurement.

Note that in the first to fourth embodiments described above, while thesubstrate position measurement system is structured by Z-tilt positionmeasurement system 98 and substrate encoder system 50, for example,instead of the X heads and Y heads, by using XZ head and YZ heads, thesubstrate position measurement system may be structured only bysubstrate encoder system 50.

Also, in the first to fourth embodiments described above, separate fromthe pair of head units 60 of substrate encoder system 50, at least onehead may be provided arranged separate from head unit 60 in the X-axisdirection. For example, a head unit the same as head unit 60 may beprovided, arranged apart from projection optical system 16 in the X-axisdirection, at each of the +Y side and the −Y side with respect to themark detection system (alignment system) that detects alignment marks ofsubstrate P, and on detection operation of the substrate marks, the pairof head units arranged on the +Y side and the −Y side of the markdetection system may be used to measure the position information ofsubstrate holder 34. In this case, on the mark detection operation, evenif all measurement beams of the pair of head units move off of scales152 (or 52), substrate encoder system 50 (the another pair of headunits) can continue to measure position information of substrate holder34, which allows the degree of freedom when designing the exposureapparatus to be increased, such as in the position of the mark detectionsystem. Note that by arranging the substrate position measurement systemmeasuring the position information of substrate P in the Z-axisdirection close to the mark detection system, substrate encoder system50 can measure the position information of substrate holder 34 also ondetection operation of the Z position of the substrate. Alternately, thesubstrate position measurement system may be arranged close toprojection optical system 16 so that the pair of head units 60 may beused to measure the position information of substrate holder 34 ondetection operation of the Z position of the substrate. Also, in theembodiments, when substrate holder 34 is arranged at a substrateexchange position set apart from projection optical system 16,measurement beams of all heads of the pair of head units 60 move off ofscales 152 (or 52). Therefore, at least one head (which may either be amovable head or a fixed head) may be provided facing at least one of theplurality of scales 152 (or 52) of substrate holder 34 arranged at thesubstrate exchange position, so that substrate encoder system 50 canmeasure the position information of substrate holder 34 also on thesubstrate exchange operation. Here, before substrate holder 34 arrivesat the substrate exchange position, or in other words, before the atleast one head arranged at the substrate exchange position faces scale152 (or 52), in the case the measurement beams move off of scales 152(or 52) in all heads of the pair of head units 60, at least one head isto be added arranged during the moving route of substrate holder 34 sothat substrate encoder system 50 can continue to measure the positioninformation of substrate holder 34. Note that in the case of using theat least one head provided separately from the pair of head units 60,the linkage process described earlier may be performed using themeasurement information of the pair of head units 60.

Also, in the first to fourth embodiments described above, the XZ headdescribed earlier may be used instead of each X head of mask encodersystem 48, along with using the YZ head described earlier instead ofeach Y head. Or, in the first to fourth embodiments described above, themask encoder system may be structured so that a plurality of heads canmove relatively with respect to scales 46 in the Y-axis direction,similar to the encoder for position measurement of substrate holder 34of substrate encoder system 50. Also, instead of scales 46, a scale maybe used, having a two-dimensional grating RG formed similar to scale 152described earlier.

Similarly, in the first to fourth embodiments described above, the XZhead described earlier may be used instead of each X head 64 x, alongwith using the YZ head described earlier instead of each Y head 64 y. Insuch a case, also instead of scales 56, a scale may be used, having atwo-dimensional grating RG formed similar to scale 152 describedearlier. In such a case, with a pair of XZ heads and a pair of YZ headsand an encoder system that these heads can face, position information ofat least one of rotation (θz) and tilt (at least one of θx and θy) of aplurality of heads 66 x and 66 y may be measured.

Note that while a grating is formed (the surface is a grating surface)on the surface of scales 46, 52, 56, 152 and the like, for example, acover member (such as glass or a thin film) that covers the grating maybe provided so that the grating surface is provided inside the scale.

Note that in the first to fourth embodiments described above, while thecase has been described in which one pair each of X head 64 x and Y head64 y are provided at Y slide table 62, along with the heads formeasuring the position of substrate holder 34, one pair each of X head64 x and Y head 64 y may be provided at the heads used for measuring theposition of substrate holder 34 without the Y slide table.

Note that in the description so far, while the case has been describedin which the measurement directions within the XY plane of each headthat the mask encoder system and the substrate encoder system areequipped with is the X-axis direction or the Y-axis direction, theembodiments are not limited to this, and for example, in the case of thesecond to fourth embodiments, instead of the two-dimensional grating RG,a two-dimensional grating may be used that intersects in the X-axisdirection and the Y-axis direction and also has periodic directions intwo directions (called α direction and β direction for convenience)orthogonal to each other, and corresponding to this, as each headdescribed earlier, heads with measurement directions in the α direction(and the Z-axis direction) or the β direction (and the Z-axis direction)may be used. Also, in the first embodiment described earlier, instead ofeach X scale and Y scale, for example, a one-dimensional grating whoseperiodic direction is in the α direction or β direction may be used, andcorresponding to this, as each head described earlier, heads withmeasurement directions in the α direction (and the Z-axis direction) orthe β direction (and the Z-axis direction) may be used.

Note that in the second to fourth embodiments described above, the firstgrating group may be structured by the row of X scales described earlierand the second grating group may be structured by the row of Y scalesdescribed earlier, and corresponding to this, a plurality of X heads (orXZ heads) that can face the X scales may be arranged at a predeterminedspacing (spacing wider than the spacing between adjacent X scales) alongwith a plurality of Y heads (or YZ heads) that can face the Y scalesbeing arranged at a predetermined spacing (spacing wider than thespacing between adjacent Y scales).

Note that in the first to fourth embodiments described above, as eachscale arranged side by side in the X-axis direction or the Y-axisdirection, a plurality of scales of different lengths may naturally beused. In this case, when two or more rows of scales having the same ororthogonal periodic directions are provided side by side, scales may bechosen with lengths that can be set so that the spacing between thescales do not overlap one another. That is, the arrangement spacing ofthe space between the scales structuring one row of scales does not haveto be an equal spacing. Also, for example, in the row of scales onsubstrate holder 34, the scales arranged in the center may have a lengthin the X-axis direction physically longer than that of the scales(scales arranged at each edge in the row of scales) arranged at bothends in the X-axis direction.

Note that in the first to fourth embodiments described above, whileencoders for movable heads only have to measure position information ofat least the movement direction (the Y-axis direction in the embodimentsdescribed above), the encoders may also measure position information ofat least one direction (at least one of X, Z, θx, θy, and θz) differentfrom the movement direction. For example, position information in theX-axis direction of a head (X head) whose measurement direction is inthe X-axis direction may also be measured, and position information inthe X-axis direction may be obtained with this X information andmeasurement information of the X head. However, with the head (Y head)whose measurement direction is in the Y-axis direction, positioninformation in the X-axis direction orthogonal to the measurementdirection does not have to be used. Similarly, with the X head, positioninformation in the Y-axis direction orthogonal to the measurementdirection does not have to be used. In short, position information ofsubstrate holder 34 in the measurement direction may be obtained,measuring position information in at least one direction different fromthe measurement direction of the heads, and by using this measurementinformation and measurement information of the heads. Also, for example,position information (rotation information) of the movable head in theθz direction may be measured using two measurement beams havingdifferent positions in the X-axis direction, and by using this rotationinformation with measurement information of the X head and the Y head,position information in the X-axis direction and the Y-axis directionmay be obtained. In this case, by arranging two of one of the X headsand Y heads and one of the other of the X heads and Y heads so that thetwo heads having the same measurement direction are not arranged at thesame position in the direction orthogonal to the measurement direction,position information in the X direction, the Y direction, and the θzdirection can be measured. The other head preferably irradiates aposition different from the two heads with the measurement beam.Moreover, if the heads of encoders for movable heads is an XZ head or aYZ head, by arranging, for example, two of one of the XZ heads and theYZ heads and the other of the XZ heads and the YZ heads so that theheads are not located on the same straight line, not only Z informationbut also position information (tilt information) in the θx direction andthe θy direction can be measured. Position information in the X-axisdirection and the Y-axis direction may be obtained by at least one ofthe position information in the θx direction and the θy direction andthe measurement information of the X heads and Y heads. Similarly, withXZ heads or YZ heads, position information in a direction different fromthe X-axis direction of the movable heads may also be measured, andposition information in the Z-axis direction may be obtained with thismeasurement information and measurement information of the movableheads. Note that when the scales of the encoders measuring the positioninformation of the movable heads is a single scale (grating area), XYθzand Zθxθy may be measured by three heads, however, in the case aplurality of scales (grating areas) are arranged separately, two each ofX heads and Y heads, or two each of XZ heads and YZ heads should bearranged and the spacing in the X-axis direction should be set so thatthe non-measurement period among the four heads do not overlap oneanother. While this explanation was made on the premise that the gratingarea is arranged parallel to the XY plane, this also can be appliedsimilarly to a scale having a grating area parallel to the YZ plane.

Also, in the first to fourth embodiments described above, while theencoder was used as the measurement device for measuring positioninformation of the movable heads, devices other than the encoder, suchas, for example, an interferometer may also be used. In this case, forexample, a reflection surface may be provided at the movable head (orits holding section) and a measurement beam parallel to the Y-axisdirection should be irradiated on the reflection surface. Especiallywhen the movable head is moved only in the Y-axis direction, thereflection surface does not have to be large, which makes it easy tolocally air-condition the optical path of the interferometer beam toreduce air fluctuation.

Also, in the first to fourth embodiments described above, while themovable heads that irradiate the scales of the substrate holder withmeasurement beams are arranged one each in the Y-axis direction on bothsides of the projection system, a plurality of movable heads may each bearranged. For example, if adjacent movable heads (measurement beams) arearranged so that the measurement period of a plurality of movable headspartly overlaps in the Y-axis direction, the plurality of movable headscan continue to measure position information even when the substrateholder moves in the Y-axis direction. In this case, linkage processbecomes necessary among the plurality of movable heads. Therefore,measurement information of a plurality of heads arranged only on oneside of the +Y side and the −Y side of the projection system irradiatingmeasurement beams on at least one scale may be used to acquirecorrection information related to another head whose measurement beam iswithin the scale, or measurement information of not only the headsarranged on the +Y side but at least one head arranged on the other sidemay also be used. In short, of the plurality of heads each arranged onthe +Y side and the −Y side, measurement information of at least threeheads irradiating measurement beams on the scale may preferably be used.

Also, with substrate encoder system 50 of the first to fourthembodiments described above, while a plurality of scales (grating areas)is arranged separately in the scanning direction (the X-axis direction)in which substrate P is moved on scanning exposure, along with aplurality of heads being movable in the stepping direction (the Y-axisdirection), conversely, the plurality of scales may be arranged in thestepping direction (the Y-axis direction) along with the plurality ofheads being movable in the scanning direction (the X-axis direction).

Also, in the first to fourth embodiments described above, the heads ofmask encoder system 48 and encoder system 50 do not necessarily have tohave all the optical system that irradiates a scale with a beam from thelight source, and may have a part of the light source, such as forexample, only the light-emitting section.

Also, in the second to fourth embodiments described above, the heads ofthe pair of head units 60 are not limited to the arrangement in FIG. 17(X heads and Y heads are arranged on the +Y side and the −Y side, and onthe +Y side and the −Y side, the arrangement of the X head and Y head onone side is opposite to the other side in the X-axis direction), and forexample, X heads and Y heads may be arranged on the +Y side and the −Yside, and on the +Y side and the −Y side, the arrangement of the X headand Y head on one side may be the same as the other side in the X-axisdirection. However, in the case the X position of two Y heads is thesame, when measurement of one of the two X heads is cut off, then the θzinformation can no longer be measured, therefore, the X position of thetwo Y heads should preferably be different.

Also, in the first to fourth embodiments described above, when thescales (scale members, grating section) irradiated with the measurementbeams from the heads of the encoder system are provided at theprojection optical system 16 side, the scales provided are not limitedto only a part of apparatus main section 18 (frame member) supportingprojection optical system 16, and may be provided at the barrel part ofprojection optical system 16.

Also, in the first to fourth embodiments described above, while the casehas been described in which the movement direction (scanning direction)of mask M and substrate P at the time of scanning exposure is in theX-axis direction, the scanning direction may be in the Y-axis direction.In this case, long stroke direction of the mask stage has to be set in adirection rotated by 90 degrees around the Z-axis, along with having torotate the direction of projection optical system 16 by 90 degreesaround the Z-axis.

Note that in the first to fourth embodiments described above, in thecase of arranging a scale group (row of scales) in which a plurality ofscales arranged in the X-axis direction is continuously arranged withgaps of a predetermined spacing in between on substrate holder 34 in aplurality of rows at different positions (e.g. a position on one side(+Y side) and a position on the other side (−Y side) with respect toprojection optical system 16) separate from each other in the Y axisdirection, a structure may be employed so that the plurality of scalegroups (plurality of rows of scales) can be used differently dependingon arrangement of shots (shot map) on the substrate. For example, bymaking the whole length of the plurality of rows of scales differentfrom one another between the rows of scales, the scales are applicableto different shot maps, and are also applicable to changes in the numberof shot areas formed on the substrate, as in the case of a four-piecesetting and the case of a six-piece setting. Also, along with thisarrangement, if position of gaps of each row of scales are made to be atdifferent positions in the X-axis direction, the heads corresponding toeach of the plurality of rows of scales do not move off away from themeasurement range simultaneously, which allows the number of sensorsconsidered as an undefined value in linkage process to be reduced andthe linkage process to be performed with high precision.

Also, in a scale group (row of scales) in which a plurality of scalesarranged in the X-axis direction is continuously arranged with gaps of apredetermined spacing in between on substrate holder 34, the length inthe X-axis direction of one scale (pattern for X-axis measurement) maybe a length that can be continuously measured only by a length of oneshot area (the length in which a device pattern is irradiated and formedon a substrate when exposure is performed while moving the substrate onthe substrate holder in the X-axis direction). This makes positionmeasurement (position control) of substrate P (substrate holder) duringscanning exposure easy, since relay control of heads with respect to theplurality of scales does not have to be performed during the scanningexposure of one shot area.

Also, in the first to fourth embodiments described above, a scale forsubstrate exchange may be provided at substrate stage device 20 oranother stage device for the substrate encoder system to acquireposition information of substrate stage device 20 moving to thesubstrate exchange position with the substrate loader, and the substrateencoder system may use the heads facing downward (such as X head 66 x)to acquire the position information of substrate stage device 20. Or, ahead for substrate exchange may be provided at substrate stage device 20or another stage device, and position information of substrate stagedevice 20 may be acquired by measuring scale 56 or the scale forsubstrate exchange.

Also, a scale for mask exchange may be provided at mask stage device 14or another stage device for the mask encoder system according to each ofthe embodiments to acquire position information of mask stage device 14moving to the mask exchange position with the mask loader, and the maskencoder system may use head unit 44 to acquire the position informationof mask stage device 14.

Also a position measurement system (e.g. a mark on a stage and anobservation system for observing the mark) separate from the encodersystem may be provided to perform exchange position control (management)of the stage.

Also, in each of the embodiments described above, while a structure isemployed of providing the scales on substrate holder 34, the scales maybe directly formed on substrate P in the exposure process. For example,the scales may be formed on scribe lines between shot areas. This allowsthe scales formed on the substrate to be measured, and based on resultsof the position measurement, nonlinear component errors can be obtainedfor each shot area on the substrate, and overlay accuracy on exposurecan also be improved based on the errors.

Note that substrate stage device 20 only has to be able to at least movesubstrate P along the horizontal plane in long strokes, and in somecases does not have to be able to perform fine position setting indirections of six degrees of freedom. The substrate encoder systemaccording to the first to fourth embodiments described above can also besuitably applied to such a two-dimensional stage device.

Also, the illumination light may be an ultraviolet light such as an ArFexcimer laser beam (wavelength 193 nm) or a KrF excimer laser beam(wavelength 248 nm), or a vacuum ultraviolet light such as an F₂ laserbeam (wavelength 157 nm). Also, as the illumination light, a harmonicwave may be used, which is a single-wavelength laser beam in theinfrared or visual region oscillated from a DFB semiconductor laser or afiber laser as vacuum ultraviolet light that is amplified by a fiberamplifier doped by, e.g. erbium (or both erbium and ytterbium), and thenis subject to wavelength conversion into ultraviolet light using anonlinear crystal. Also, a fixed laser (wavelength: 355 nm, 266 nm) mayalso be used.

Also, while the case has been described where projection optical system16 is a projection optical system of a multiple lens method equippedwith a plurality of optical systems, the number of projection opticalsystems is not limited to this, and one or more will be fine. Also, theprojection optical system is not limited to the projection opticalsystem of a multiple lens method, and may also be an Offner typeprojection optical system which uses a large mirror. Also, as projectionoptical system 16, a magnifying system or a reduction system may also beused.

Also, the exposure apparatus is not limited to the exposure apparatusfor liquid crystals which transfers the liquid crystal display devicepattern onto a square-shaped glass plate, and may also be widelyapplied, for example, to an exposure apparatus for manufacturing organicEL (Electro-Luminescence) panels, an exposure apparatus formanufacturing semiconductors, or to an exposure apparatus formanufacturing thin film magnetic heads, micromachines, and DNA chips.Also, the above embodiments can be applied not only to an exposureapparatus for manufacturing microdevices such as semiconductors, butalso to an exposure apparatus that transfers a circuit pattern onto aglass substrate or a silicon wafer to manufacture a reticle or a maskused in an optical exposure apparatus, an EUV exposure apparatus, anX-ray exposure apparatus, and an electron-beam exposure apparatus.

Also, the object subject to exposure is not limited to a glass plate,and may also be other objects, such as, for example, a wafer, a ceramicsubstrate, a film member, or a mask blanks. Also, in the case theexposure object is a substrate for a flat panel display, the thicknessof the substrate is not limited in particular, and includes, forexample, a film-like substrate (a sheet-like member having flexibility).Note that the exposure apparatus of the embodiments is especiallyeffective in the case when the exposure object is a substrate whoselength of a side or diagonal length is 500 mm or more.

Electronic devices such as liquid crystal display devices (orsemiconductor devices) are manufactured through the steps such as; astep for performing function/performance design of a device, a step formaking a mask (or a reticle) on the basis of this design step, a stepfor making a glass substrate (or a wafer), a lithography step fortransferring a pattern of a mask (reticle) onto the glass substrate bythe exposure apparatus and the exposure method described in each of theabove embodiments, a development step for developing the glass substratewhich has been exposed, an etching step for removing by etching anexposed member of an area other than the area where the resist remains,a resist removing step for removing the resist that is no longernecessary since etching has been completed, a device assembly step, andan inspection step. In this case, in the lithography step, because thedevice pattern is formed on the glass substrate by carrying out theexposure method previously described using the exposure apparatus of theembodiments described above, a highly integrated device can bemanufactured with good productivity.

Note that the disclosures of U.S. Patent Application Publications andU.S. Patents related to the exposure apparatus and the like quoted ineach of the embodiments above, in their entirety, are incorporatedherein by reference as a part of the present specification.

INDUSTRIAL APPLICABILITY

As is described so far, the exposure apparatus and the exposure methodof the present invention is suitable for performing exposure byirradiating and object with an illumination light in a lithographyprocess. Also, the flat panel display manufacturing method of thepresent invention is suitable for producing flat panel displays.

REFERENCE SIGNS LIST

-   10 . . . liquid crystal exposure apparatus,-   14 . . . mask stage device,-   20 . . . substrate stage device,-   34 . . . substrate holder,-   40 . . . mask holder,-   44 . . . head unit,-   46 . . . scale,-   48 . . . mask encoder system,-   50 . . . substrate encoder system,-   52 . . . scale,-   56 . . . scale,-   60 . . . head unit,-   90 . . . main controller,-   M . . . mask,-   P . . . substrate.

The invention claimed is:
 1. An exposure method irradiating an objectwith an illumination light via an optical system, comprising: measuringposition information of a movable body in at least directions of threedegrees of freedom within a predetermined plane orthogonal to an opticalaxis of the optical system by a measurement system in which one of agrating member with a plurality of grating areas arranged apart from theplurality of first grating areas in a second direction orthogonal to thefirst direction within the predetermined plane and apart from oneanother in the first direction, and a plurality of heads eachirradiating the grating member with a measurement beam that can move inthe second direction orthogonal to the first direction within thepredetermined plane is provided at the movable body, and the other ofthe grating member and the plurality of heads is provided facing themovable body, and by the measurement system having a measurement devicethat measures position information of the plurality of heads in thesecond direction, position information of the movable body is measuredbased on measurement information of at least three heads of theplurality of heads irradiating at least one of the plurality of gratingareas with the measurement beams and measurement information of themeasurement device; and moving the movable body based on positioninformation measured by the measurement system; wherein with each of theplurality of heads, the measurement beam moves off one of the pluralityof grating areas, and moves to irradiate another grating area adjacentto the one grating area while the movable body is moving in the firstdirection.
 2. The exposure method according to claim 1, wherein each ofthe plurality of heads has a measurement direction in one of twodirections intersecting each other in the predetermined plane, and theat least three heads used for measurement in the measurement systeminclude at least one head whose measurement direction is one of the twodirections and at least two heads whose measurement direction is theother of the two directions.
 3. The exposure method according to claim2, wherein the plurality of heads includes at least two heads whosemeasurement direction is in the first direction and at least two headswhose measurement direction is in the second direction.
 4. The exposuremethod according to claim 1, wherein the plurality of heads includes ahead whose measurement direction is in a direction different from thefirst direction in the predetermined plane, and measurement informationof the measurement device is used to measure position information of themovable body using the head whose measurement direction is differentfrom the first direction.
 5. The exposure method according to claim 4,wherein the plurality of heads includes at least two heads whosemeasurement direction is in the first direction and at least two headswhose measurement direction is in the second direction.
 6. The exposuremethod according to claim 1, wherein the plurality of heads can berelatively moved with the movable body in the second direction.
 7. Theexposure method according to claim 1, wherein the plurality of headsincludes two heads irradiating the measurement beams at a spacing widerthan a pair of adjacent grating areas of the plurality of grating areasin the first direction, and at least one head whose position of themeasurement beam is different from at least one of the two heads in thesecond direction.
 8. The exposure method according to claim 1, whereineach of the plurality of grating areas has one of a reflectivetwo-dimensional grating and two reflective one-dimensional gratingswhose arrangement direction is different from each other.
 9. Theexposure method according to claim 1, wherein each of the plurality ofgrating areas is formed on a plurality of scales different from oneanother.
 10. The exposure method according to claim 1, wherein the atleast three heads used for measurement in the measurement system aremoved so that each of the measurement beams of the at least three headsdoes not move off of the plurality of grating areas in the seconddirection while the movable body is moving.
 11. The exposure methodaccording to claim 1, wherein one or a plurality of heads of theplurality of heads each is held by each of a plurality of movablesections, and position information of the head is measured by themeasurement device at each of the plurality of movable sections.
 12. Theexposure method according to claim 1, wherein in each of the pluralityof heads, measurement direction is in two directions that are one of twodirections intersecting each other within the predetermined plane, and athird direction orthogonal to the predetermined plane, and positioninformation of the movable body is measured in directions of threedegrees of freedom including the third direction, which is differentfrom the directions of three degrees of freedom, using the at leastthree heads.
 13. The exposure method according to claim 1, wherein theplurality of heads has at least four heads, and while the measurementbeam of one head of the at least four heads moves off of the pluralityof grating areas, the measurement beams of at least three headsremaining are to irradiate at least one of the plurality of gratingareas, and by the movable body moving in the first direction, the onehead whose measurement beam moves off of the plurality of grating areasis switched among the at least four heads.
 14. The exposure methodaccording to claim 13, wherein the at least four heads include two headswhose position of the measurement beam is different from each other inthe first direction, and two heads whose position of the measurementbeam is different from at least one of the two heads in the seconddirection and position of the measurement beam is different from eachother in the first direction, and the two heads whose position of themeasurement beam is different from each other in the first directionirradiate the measurement beams at a spacing wider than a spacingbetween a pair of adjacent grating areas of the plurality of gratingareas in the first direction.
 15. The exposure method according to claim13, wherein the grating member has at least two of the plurality ofgrating areas arranged apart from each other in the second direction,and on each of the at least two of the plurality of grating areas, themeasurement beam is irradiated via the at least two heads whose positionof the measurement beam is different from each other in the firstdirection, and the at least two heads irradiate the measurement beams ata spacing wider than a spacing between a pair of adjacent grating areasof the plurality of grating areas in the first direction.
 16. Theexposure method according to claim 15, wherein the grating member isprovided at the movable body, and the at least two of the plurality ofgrating areas includes a pair of the plurality of grating areas arrangedon both sides of an object mounting area of the movable body in thesecond direction.
 17. The exposure method according to claim 13, whereinnon-measurement section in which the measurement beams of the at leastfour heads move off the plurality of grating areas in the at least fourheads does not overlap while the movable body is moving in the firstdirection.
 18. The exposure method according to claim 17, wherein theplurality of heads includes at least one head whose non-measurementsection at least partly overlaps with the non-measurement section of atleast one of the at least four heads, and in measurement of positioninformation of the movable body, of at least five heads including the atleast four heads and the at least one head, measurement information isused of at least three heads irradiating at least one of the pluralityof grating areas with the measurement beam.
 19. The exposure methodaccording to claim 13, wherein correction information to controlmovement of the movable body is acquired, using one head of the at leastfour heads whose measurement beam moves off of the one grating area andmoves to irradiate the another grating area, based on measurementinformation of at least three heads remaining, or position informationof the movable body measured using the at least three heads remaining.20. The exposure method according to claim 19, wherein the correctioninformation is acquired while each of the measurement beams of the atleast four heads irradiates at least one of the plurality of gratingareas.
 21. The exposure method according to claim 19, wherein positioninformation of the movable body is measured, using at least three headsincluding the one head whose correction information has been acquired,instead of one head of the at least three heads remaining, before themeasurement beam of the one head of the at least three heads remainingmoves off of the plurality of grating areas.
 22. The exposure methodaccording to claim 19, wherein each of the plurality of heads has ameasurement direction in two directions that are one of two directionsintersecting each other within the predetermined plane and a thirddirection orthogonal to the predetermined plane, and positioninformation of the movable body is measured in directions of threedegrees of freedom including the third direction, which is differentfrom the directions of three degrees of freedom, using the at leastthree heads, and correction information to control movement of themovable body in the different directions of three degrees of freedom isacquired, using one head of the at least four heads irradiating themeasurement beam that moves off of the one grating area and moves toirradiate the another grating area, based on measurement information inthe third direction of at least three heads remaining, or positioninformation of the movable body in the different directions of threedegrees of freedom measured using the at least three heads remaining.23. The exposure method according to claim 1, wherein the other of thegrating member and the plurality of heads is provided at a frame membersupporting the projection optical system.
 24. The exposure methodaccording to claim 1, wherein position information of the plurality ofheads is measured by the measurement device in which one of a scalemember and a second head is provided at the plurality of heads and theother of the scale member and the second head is provided facing theplurality of heads, the measurement device irradiating the scale memberwith a measurement beam via the second head.
 25. The exposure methodaccording to claim 24, wherein one of the scale member and the secondhead is provided at the plurality of heads, and the other of the scalemember and the second head is provided at one of the projection opticalsystem and a frame member supporting the projection optical system. 26.The exposure method according to claim 25, wherein the grating member isprovided at the movable body, and the plurality of heads is provided atthe frame member, the second head is provided at the plurality of heads,and the scale member is provided at the frame member.
 27. The exposuremethod according to claim 25, wherein a plurality of the measurementbeams is irradiated at positions mutually different on the scale member,and position information of the plurality of heads is measured in adirection different from the second direction.
 28. The exposure methodaccording to claim 25, wherein position information on one of rotationand tilt of the plurality of heads is measured by the measurementdevice.
 29. The exposure method according to claim 25, wherein the scalemember has at least one of a reflective two-dimensional grating and tworeflective one-dimensional gratings whose arrangement direction isdifferent from each other.
 30. The exposure method according to claim24, wherein the scale member has a plurality of grating sectionsarranged mutually separate in the second direction, the measurementsystem measures position information of the plurality of heads by themeasurement device having a plurality of the second heads including atleast two of the second heads whose position of the measurement beams isdifferent in the second direction, and the at least two of the secondheads irradiate the measurement beams at a spacing wider than a pair ofadjacent grating sections of the plurality of grating sections in thesecond direction.
 31. The exposure method according to claim 30, whereinthe plurality of second heads include at least one second head whoseposition of the measurement beam is different from at least one of theat least two of the second heads in one of the first direction and athird direction orthogonal to the predetermined plane.
 32. The exposuremethod according to claim 30, wherein a plurality of the measurementbeams is irradiated at positions mutually different on the scale member,and position information of the plurality of heads is measured in adirection different from the second direction.
 33. The exposure methodaccording to claim 30, wherein position information on one of rotationand tilt of the plurality of heads is measured by the measurementdevice.
 34. The exposure method according to claim 30, wherein the scalemember has at least one of a reflective two-dimensional grating and tworeflective one-dimensional gratings whose arrangement direction isdifferent from each other.
 35. The exposure method according to claim 1,wherein the object is a mask illuminated with the illumination light viathe optical system.
 36. The exposure method according to claim 35,wherein the other of the grating member and the plurality of heads isprovided at one of the projection system and a frame member supportingthe projection system, and the projection system projecting a pattern ofthe mask on a substrate has a plurality of projection optical systemseach projecting a partial image of the pattern on projection areas ofmutually different positions.
 37. The exposure method according to claim1, wherein the object is a substrate exposed with the illumination lightvia the optical system.
 38. The exposure method according to claim 37,wherein position information of a holding member that can move holding amask illuminated with the illumination light is measured by an encodersystem in which one of a scale member and a third head is provided atthe holding member and the other of the scale member and the third headis provided at one of the projection system and a frame membersupporting the projection system.
 39. The exposure method according toclaim 37, wherein the optical system has a plurality of projectionoptical systems, and each of a partial image of a pattern of the maskilluminated with the illumination light is projected on the substratevia the plurality of projection optical systems.
 40. The exposure methodaccording to claim 39, wherein the substrate is scanned and exposed withthe illumination light via the projection optical system, and theplurality of projection optical systems each projects the partial imagein a plurality of projection areas of mutually different positions in adirection orthogonal to a scanning direction in which the substrate ismoved on the scan and exposure.
 41. The exposure method according toclaim 37, wherein the substrate is scanned and exposed with theillumination light via the projection system, and is moved in one of thefirst direction and the second direction on the scan and exposure. 42.The exposure method according to claim 37, wherein the substrate has atleast one of a length of a side and a diagonal length that is 500 mm ormore, and is used in a flat panel display.
 43. A flat panel displaymanufacturing method, comprising: exposing a substrate using theexposure method according to claim 1; and developing the substrate thathas been exposed.